JP2010037185A - GaN CRYSTAL SUBSTRATE, GaN CRYSTAL SUBSTRATE MANUFACTURING METHOD, GaN CRYSTAL SUBSTRATE PROVIDED WITH SEMICONDUCTOR EPITAXIAL LAYER, SEMICONDUCTOR DEVICE AND SEMICONDUCTOR DEVICE MANUFACTURING METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a GaN crystal substrate which has large effects of collecting dislocations and low dislocation density in a low dislocation density crystal region even with a large pitch of a high dislocation density crystal region and has a small warpage, and to provide a method for manufacturing the same. <P>SOLUTION: The GaN crystal substrate 20p has a main face 20m having an off angle of 0-30° to a (0001) plane and includes a low dislocation density crystal region 20k and a high dislocation density crystal region 20h. The high dislocation density crystal region 20h on the main face 20m has a shape of a lattice which includes a plurality of first stripe crystal regions 20hs extending in a [1-100] direction and a plurality of second stripe crystal regions 20ht extending in a [11-20] direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a GaN crystal substrate suitably used for manufacturing a semiconductor device such as a light emitting device and an electronic device, and a manufacturing method thereof. Specifically, the present invention relates to a GaN crystal substrate including a low dislocation density crystal region and a manufacturing method thereof.

  GaN crystal substrates are widely used in semiconductor devices such as light emitting devices and electronic devices. In order to improve the physical properties of semiconductor devices, development of GaN crystal substrates with low dislocation density is underway.

  For example, Japanese Patent Laid-Open No. 2003-165799 (referred to as Patent Document 1, hereinafter the same) discloses dislocation on a dot-like seed crystal by arranging a dot-like seed crystal on a base substrate and performing facet growth of a GaN crystal. Is used to form a dot-like high dislocation density crystal region, and a GaN crystal substrate having a low dislocation density crystal region formed thereby is disclosed.

  Japanese Patent Laying-Open No. 2003-183100 (referred to as Patent Document 2 hereinafter) collects dislocations on a stripe-shaped mask by arranging a stripe-shaped mask on a base substrate and performing facet growth of a GaN crystal. A method for manufacturing a GaN crystal substrate having a low dislocation density crystal region formed by forming a stripe-like high dislocation density crystal region is disclosed.

JP 2003-165799 A JP 2003-183100 A

  However, in the method of Patent Document 1, the dot-like high dislocation density crystal region in which dislocations concentrate and have a high dislocation density is extremely smaller than the entire crystal region, so that the dislocation is transferred to the dot-like high dislocation density crystal region. Is low, and the effect of reducing the dislocation density in the low dislocation density crystal region is low. Also, in order to widen the low dislocation density crystal region, increasing the pitch of the dot-like high dislocation density crystal region where the dislocations concentrate to give a high dislocation density has the effect of collecting dislocations in the dot-like high dislocation density crystal region. This further decreases the effect of reducing the dislocation density in the low dislocation density crystal region.

  Also in the method of Patent Document 2, in order to widen the low dislocation density crystal region, when the pitch of the stripe-shaped high dislocation density crystal region in which dislocations concentrate and become a high dislocation density is increased, a dot shape or a stripe shape is obtained. The effect of collecting dislocations in the high dislocation density crystal region is reduced, and the effect of reducing the dislocation density in the low dislocation density crystal region is reduced.

  In addition, the GaN crystal is likely to warp due to dislocations generated when growing on a different kind of base substrate having a chemical composition different from that of the GaN crystal and internal stress generated by propagation of the dislocations. For this reason, the plane orientation shifts between the central portion and the peripheral portion of the main surface of the GaN crystal substrate. On the other hand, by forming a stripe-shaped high dislocation density crystal region, the propagation of dislocations is suppressed in the direction parallel to the stripe direction, and the plane orientation of the central portion and the peripheral portion of the main surface of the GaN crystal substrate Can be mitigated. However, even when the stripe-shaped high dislocation density crystal region is formed, the deviation of the plane orientation between the central portion and the peripheral portion of the main surface of the GaN crystal substrate in the direction perpendicular to the stripe direction cannot be reduced. .

Further, even when a Schottky barrier diode, which is a semiconductor device, is manufactured using a GaN crystal substrate having a distance between stripe-like high dislocation density crystal regions of 400 μm or more, there is a problem that the reverse withstand voltage is lowered. When a low dislocation density crystal region having a width of 400 μm or more of the GaN crystal substrate is observed by CL (cathode luminescence), dislocations are locally 1 × 10 ⁷ cm ⁻² in a portion near the high dislocation density crystal region in the low dislocation density crystal region. A plurality of dislocation concentration regions concentrated as described above were observed as dark portions. More dislocation concentration regions were observed as the spacing between the high dislocation density crystal regions was increased, that is, as the width of the low dislocation density crystal regions was increased. Moreover, the dislocation concentration region in the GaN crystal substrate in the semiconductor device has been a cause of reduction in the withstand voltage of the semiconductor device.

  The present invention solves the above-described problems, has a large effect of collecting dislocations even when the pitch of the high dislocation density crystal region is large, a low dislocation density in the low dislocation density crystal region, and a GaN crystal substrate having a small uniform warpage and its An object of the present invention is to provide a manufacturing method, a GaN crystal substrate with an epitaxial layer including the GaN crystal substrate, a semiconductor device including the GaN crystal substrate, and a manufacturing method thereof.

  The present invention has a main surface having an off angle of 0 ° to 30 ° with respect to the (0001) plane, and includes a low dislocation density crystal region and a high dislocation density crystal region, and a high dislocation density crystal in the main surface. The shape of the region is a GaN crystal substrate having a lattice shape including a plurality of first stripe crystal regions extending in the [1-100] direction and a plurality of second stripe crystal regions extending in the [11-20] direction. Here, the off angle of the main surface means an off angle at the center point of the main surface.

In the GaN crystal substrate according to the present invention, the first stripe crystal region may have a width of 5 μm to 120 μm and a pitch of 200 μm to 10,000 μm, and the second stripe crystal region may have a width of 5 μm to 120 μm and a pitch of 200 μm. The thickness can be set to 10000 μm or less. The high dislocation density crystal region can be a polarity inversion crystal region in which the polarity in the [0001] direction is reversed with respect to the low dislocation density crystal region. The low dislocation density crystal region includes a (0001) plane growth crystal region and a facet growth crystal region, and a ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region on the main surface is 0.7. It can be as follows. Further, the first deviation angle, which is the difference between the off angle at the center of the main surface and the off angle at the end in the [1-100] direction from the center, and the off angle and the center at the center of the main surface [11-20. The second deviation angle, which is the difference between the off-angle at the end of the direction, is 0 ° C. or more and 0.30 ° or less, and the difference between the first deviation angle and the second deviation angle is 0 ° C. or more and 0.30. It can be below. Further, the first stripe crystal region or the second stripe crystal region can be discontinuous at least at one location. The carrier concentration can be set to 1 × 10 ¹⁸ cm ⁻³ or more and 1.2 × 10 ¹⁹ cm ⁻³ or less. In addition, the low dislocation density crystal region can have dislocation concentration regions of 0.1 / region to 5.5 / region per region surrounded by the high dislocation density crystal region.

  The present invention is also a method for manufacturing the above GaN crystal substrate, wherein the main surface has an off angle of 0 ° or more and 30 ° or less with respect to the plane orientation of the base substrate corresponding to the (0001) plane of the GaN crystal substrate. A plurality of first stripe masks extending in a first direction corresponding to the [1-100] direction of the GaN crystal substrate on the main surface of the base substrate, and [11- 20] forming a mask having a lattice pattern including a plurality of second stripe masks extending in a second direction corresponding to the direction, and growing a GaN crystal on the main surface of the base substrate on which the mask is formed And a step of forming a main surface parallel to the main surface of the base substrate on the GaN crystal to obtain a GaN crystal substrate. In the step of growing the GaN crystal, the (000-1) plane of the GaN crystal grows on the mask, and the (0001) plane of the GaN crystal grows at the center of the opening of the mask of the base substrate. In this part, the GaN crystal is faceted. Thus, a GaN crystal including a low dislocation density crystal region formed by (0001) plane growth and facet growth and a high dislocation density crystal region formed by (000-1) plane growth grows. In the method for manufacturing a GaN crystal substrate according to the present invention, the first stripe mask or the second stripe mask can be discontinuous at least at one location.

  The present invention also includes the above GaN crystal substrate and at least one group III nitride semiconductor epitaxial layer formed on the GaN crystal substrate, wherein the group III nitride semiconductor epitaxial layer is a low-power GaN crystal substrate. A GaN crystal substrate with a semiconductor epitaxial layer, comprising a low dislocation density epitaxial crystal region formed immediately above the dislocation density crystal region and a high dislocation density epitaxial crystal region formed immediately above the high dislocation density crystal region of the GaN crystal substrate It is.

The present invention also provides the GaN crystal substrate, at least one group III nitride semiconductor epitaxial layer formed on one main surface of the GaN crystal substrate, and a main surface of the group III nitride semiconductor epitaxial layer. An electrode formed on at least one of the upper surface and the other main surface of the GaN crystal substrate, the GaN crystal substrate having a size of 400 μm square or more and a dislocation density of less than 1 × 10 ⁷ cm ⁻² It is a certain semiconductor device. In the semiconductor device according to the present invention, the GaN crystal substrate includes a (0001) plane growth crystal region and a facet growth crystal region, and (0001) plane growth with respect to the area of the facet growth crystal region on one main surface of the GaN crystal substrate. The ratio of the areas of the crystal regions can be 0.2 or more and 0.7 or less.

  The present invention also provides a step of preparing the above GaN crystal substrate, a step of growing at least one group III nitride semiconductor epitaxial layer on the GaN crystal substrate, and a direct conversion of the low dislocation density crystal region of the GaN crystal substrate. Forming an electrode on at least one of the group III nitride semiconductor epitaxial layer and the GaN crystal substrate in the upper and lower regions, and a method for manufacturing a semiconductor device.

  According to the present invention, even if the pitch of the high dislocation density crystal region is large, the effect of collecting dislocations is large, the dislocation density of the low dislocation density crystal region is low, and the warpage is small, and the manufacturing method thereof, and the GaN crystal substrate An epitaxial layer-attached GaN crystal substrate including the semiconductor device, a semiconductor device including the GaN crystal substrate, and a method for manufacturing the semiconductor device can be provided.

It is the schematic which shows an example of the GaN crystal substrate concerning this invention. Here, (a) is a schematic plan view, (b) is a schematic cross-sectional view at IB-IB in (a), and (c) is a schematic cross-sectional view at IC-IC in (a). It is the schematic which shows an example of the base substrate used for manufacture of the GaN crystal substrate concerning this invention, and mask formation. Here, (a) is a schematic plan view, (b) is a schematic cross-sectional view taken along IIB-IIB in (a), and (c) is a schematic cross-sectional view taken along IIC-IIC in (a). It is a schematic sectional drawing which shows an example of the manufacturing method of the GaN crystal substrate concerning this invention. Here, (a) is a schematic sectional view in the (1-100) plane of the GaN crystal substrate, and (b) is a schematic sectional view in the (11-20) plane of the GaN crystal substrate. It is the schematic which shows an example of a typical GaN crystal substrate. Here, (a) is a schematic plan view, and (b) is a schematic cross-sectional view taken along IVB-IVB in (a). It is the schematic which shows an example of the base substrate used for manufacture of a typical GaN crystal substrate, and mask formation. Here, (a) is a schematic plan view, and (b) is a schematic cross-sectional view at VB-VB in (a). The schematic sectional drawing in the (1-100) plane of a GaN crystal substrate which shows an example of the manufacturing method of the GaN crystal substrate concerning this invention is shown. It is a schematic plan view which shows the example of the additional mask of the hexagonal lattice shape which has the some hexagonal micro opening part in A part of Fig.2 (a). Here, (a) shows an example of the arrangement of the micro openings, and (b) shows another example of the arrangement of the micro openings. FIG. 3 is a schematic plan view showing a stripe-shaped additional mask having a plurality of stripe-shaped micro openings in a portion A of FIG. Here, (a) shows an example of the arrangement of the micro openings, and (b) shows another example of the arrangement of the micro openings. It is a schematic plan view which shows an example of the additional mask of the hexagonal lattice shape which has the some hexagonal micro opening part in B part of Fig.5 (a). It is the schematic which shows the other example of the GaN crystal substrate concerning this invention. Here, (a) is a schematic plan view, (b) is a schematic cross-sectional view at XB-XB in (a), and (c) is a schematic cross-sectional view at XC-XC in (a). It is the schematic which shows the other example of the base substrate used for manufacture of the GaN crystal substrate concerning this invention, and mask formation. Here, (a) is a schematic plan view, (b) is a schematic cross-sectional view at XIB-XIB in (a), and (c) is a schematic cross-sectional view at XIC-XIC in (a). It is the schematic which shows an example of the GaN crystal substrate with a semiconductor epitaxial layer concerning this invention. Here, (a) is a schematic plan view, (b) is a schematic cross-sectional view at XIIB-XIIB in (a), and (c) is a schematic cross-sectional view at XIIC-XIIC in (a). Another example of a GaN crystal substrate with a semiconductor epitaxial layer according to the present invention is a GaN crystal substrate with a semiconductor epitaxial layer in which the main surface of the substrate has an off-angle and the first stripe crystal region and the second stripe crystal region are continuous. It is a schematic plan view shown. Still another example of a GaN crystal substrate with a semiconductor epitaxial layer according to the present invention is a semiconductor epitaxial in which the main surface of the substrate has an off angle and the first stripe crystal region or the second stripe crystal region is discontinuous at least at one location. It is a schematic plan view which shows a GaN crystal substrate with a layer. It is the schematic which shows an example of the manufacturing method of the semiconductor device concerning this invention. Here, (a) is a schematic plan view, (b) is a schematic cross-sectional view at XVB-XVB in (a), and (c) is a schematic cross-sectional view at XVC-XVC in (a). It is the schematic which shows an example of the semiconductor device obtained by the manufacturing method of the semiconductor device concerning this invention. Here, (a) is a schematic plan view, and (b) is a schematic cross-sectional view taken along XVIB-XVIB in (a). It is the schematic which shows the other example of the manufacturing method of the semiconductor device concerning this invention. Here, (a) is a schematic plan view, (b) is a schematic cross-sectional view taken along XVIIB-XVIIB in (a), and (c) is a schematic cross-sectional view taken along XVIIC-XVIIC in (a). It is the schematic which shows the other example of the semiconductor device obtained by the manufacturing method of the semiconductor device concerning this invention. Here, (a) is a schematic plan view, and (b) is a schematic cross-sectional view taken along XVIIIB-XVIIIB in (a). It is a schematic sectional drawing which shows the C part and D part of FIG. Here, (a) shows a portion C in FIG. 17 (2), and (b) shows a portion D in FIG. 17 (3).

(Embodiment 1)
Referring to FIG. 1, an embodiment of a GaN crystal substrate according to the present invention has a main surface 20m having an off angle of 0 ° or more and 30 ° or less with respect to the (0001) plane, and a low dislocation density crystal region. The shape of the high dislocation density crystal region 20h in the main surface 20m includes a plurality of first stripe crystal regions 20hs extending in the [1-100] direction and the [11-20] direction. The lattice shape includes a plurality of second stripe crystal regions 20ht extending.

  The main surface 20m of the GaN crystal substrate 20p of this embodiment has an off angle of 0 ° to 30 ° with respect to the (0001) plane. Here, the off angle of the main surface 20m means an off angle at the center point of the main surface 20m. Therefore, various semiconductor devices can be manufactured by growing a group III nitride crystal layer on the main surface 20m of the GaN crystal substrate 20p with the (0001) plane as the crystal growth surface. From the viewpoint of facilitating growth with the (0001) plane of the group III nitride crystal as the crystal growth plane, the off angle of the main surface 20m with respect to the (0001) plane of the GaN crystal substrate 20p is preferably 0 ° or more and 25 ° or less. 0 ° or more and 10 ° or less is more preferable.

  On the other hand, referring to FIG. 12, when the off angle of main surface 20m of GaN crystal substrate 20p is 0 ° (that is, main surface 20m is (0001) surface), a group III nitride semiconductor epitaxial layer is formed on main surface 20m. Since the step flow growth is hindered because a plane parallel to the main surface 20m (that is, the (0001) plane) is grown as a crystal growth plane, impurity incorporation into the group III nitride semiconductor epitaxial layer 30 is caused. Becomes non-uniform, and the breakdown voltage yield of the resulting semiconductor device decreases.

  12 and 13, the main surface 20m of the GaN crystal substrate 20p is, for example, in the [1-100] direction with respect to the (0001) plane (this is the direction in which the first stripe crystal region 20hs extends). )) Is grown on the main surface 20m of the GaN crystal substrate 20p having an off angle larger than 0.05 ° and smaller than 1 °, [1-100] of the GaN crystal substrate 20p is grown. A region immediately above a region slightly entering in the [1-100] direction from the region in contact with the second stripe crystal region 20ht extending in the [11-20] direction perpendicular to the direction into the low dislocation density crystal region 20k (such region) Is equivalent to the epitaxial abnormal growth region 30ei described later), the (0001) plane is grown as the crystal growth surface, and in the other regions, the main surface is flat. A growth plane (this is a plane having the above-mentioned small off angle with respect to the (0001) plane) is grown as a crystal growth plane. In group III nitride semiconductor epitaxial layer 30 grown on main surface 20m of GaN crystal substrate 20p having main surface 20m having a small off-angle as described above with respect to (0001) surface, crystal growth is performed on (0001) surface. A region that grows as a plane is called an epitaxial abnormal growth region 30ei, and lowers the withstand voltage of a semiconductor device including the region.

  From the viewpoint of reducing the above-described epitaxial abnormal growth region 30ei, the off angle of the main surface 20m of the GaN crystal substrate 20p is preferably 0 ° or more and 0.05 ° or less, or 1 ° or more and 25 ° or less. Here, if the off angle of the main surface 20m is larger than 0.05 ° and smaller than 1 °, an epitaxially abnormal growth region is formed, and the carrier intake in the region is different. In such a case, as will be described later, the formation of the epitaxially abnormal growth region can be suppressed by making the stripe crystal region extending in the direction perpendicular to the off direction of the off angle discontinuous. In such a case, when the group III nitride semiconductor epitaxial layer is grown on the GaN crystal substrate, an excellent step flow is performed, so that an epitaxial layer having a uniform carrier concentration can be obtained. By setting the off angle to 0 ° or more and 0.05 ° or less, the epitaxial growth becomes favorable and the formation of the epitaxial abnormal growth region can be suppressed. Moreover, even if the off angle is 1 ° or more, the formation of the epitaxial abnormal growth region can be suppressed. However, when the off angle is larger than 25 °, when the GaN crystal is grown using the GaAs substrate as the base substrate, the GaN crystal grown on the main surface of the GaAs substrate having a large off angle with respect to the GaAs (111) A plane is Epitaxial growth is not performed and polycrystallizes. The epitaxial abnormal growth region 30ei is obtained by measuring the height distribution of the crystal growth surface of the epitaxial layer using a laser microscope.

  Further, in the GaN crystal substrate 20p of the present embodiment, the first deviation angle that is the difference between the off angle at the center of the main surface and the off angle at the end in the [1-100] direction from the center and the center of the main surface The second deviation angle, which is the difference between the off angle at the center and the off angle at the end in the [11-20] direction from the center, is preferably 0 ° or more and 0.30 ° or less, and the first deviation angle and the second deviation angle. The difference from the angle is preferably 0 ° or more and 0.30 ° or less. The first deviation angle and the second deviation angle are preferably small from the viewpoint of reducing the maximum on-resistance of the device obtained by reducing the variation in carrier concentration on the main surface 20m, for example, 0 ° or more and 0.30 °. Or less, more preferably 0 ° or more and 0.10 ° or less. On the other hand, considering the workability of manufacturing from the current manufacturing technology of the GaN crystal substrate 20p, the first deviation angle and the second deviation angle are preferably about 0.01 ° or more. Further, since the difference between the first deviation angle and the second deviation angle causes variation in the carrier concentration of the group III nitride semiconductor epitaxial layer grown on the GaN crystal substrate, a smaller one is preferable, for example, 0 ° or more and 0 It is preferably 30 ° or less, and more preferably 0 ° or more and 0.10 ° or less.

  Here, the first deviation angle is determined by the ω-rocking curve in the (0002) plane of the GaN crystal by X-ray diffraction with respect to the plane orientation at the center of the main surface and the plane orientation at the end in the [1-100] direction from the center. It is obtained by measuring and calculating the difference between the two. Further, the first deviation angle is measured by the ω-rocking curve on the (0002) plane of the GaN crystal by X-ray diffraction with respect to the plane orientation at the center of the main surface and the plane orientation at the end in the [1-100] direction from the center. It is obtained by calculating the difference between the two. The second deviation angle is measured by the ω-rocking curve in the (0002) plane of the GaN crystal by X-ray diffraction, with the plane orientation at the center of the main surface and the plane orientation at the end in the [11-20] direction from the center, It is obtained by calculating the difference between the two.

  The GaN crystal substrate 20p of this embodiment includes a low dislocation density crystal region 20k and a high dislocation density crystal region 20h. The GaN crystal substrate 20p reduces the dislocation density in regions other than the high dislocation density crystal region 20h by collecting dislocations in the crystal in a predetermined region during crystal growth to form a high dislocation density crystal region 20h. A low dislocation density crystal region 20k is formed. In the GaN crystal substrate 20p, one or more group III nitride crystal layers can be grown on the low dislocation density crystal region 20k to manufacture various semiconductor devices having good characteristics.

In the GaN crystal substrate 20p of this embodiment, the shape of the high dislocation density crystal region 20h on the main surface 20m is a plurality of first stripe crystal regions 20hs extending in the [1-100] direction and a plurality of extending in the [11-20] direction. And a second stripe crystal region 20ht. Since the GaN crystal substrate 20p of this embodiment has the high dislocation density crystal region 20h having such a shape, dislocations are collected in the high dislocation density crystal region 20h surrounding the four sides of the low dislocation density crystal region 20k. Even if the pitch P ₁ of the first stripe crystal region 20 hs and the pitch P _{2 of} the second stripe crystal region 20 ht of the crystal region 20 h are increased, the dislocation density of the low dislocation density crystal region 20 k can be sufficiently lowered.

On the other hand, referring to FIG. 4, a typical GaN crystal substrate 20p is a plurality of first stripe crystal regions in which a high dislocation density crystal region 20h extends in a stripe shape in the [1-100] direction. When the pitch P ₁ of the first stripe crystal region is increased, the effect of collecting dislocations in the high dislocation density crystal region 20h is reduced, and the dislocation density in the low dislocation density crystal region 20k cannot be sufficiently reduced.

  In addition, the GaN crystal substrate 20p of the present embodiment has a plurality of first stripe crystal regions 20hs and [11] in which a high dislocation density crystal region 20h that relaxes crystal warpage that occurs during crystal growth extends in the [1-100] direction. −20] in the direction parallel to the [1-100] direction and the direction parallel to the [11-20] direction, the central portion and the periphery of the GaN crystal substrate are included. Deviation of the plane orientation with the part can be reduced.

  On the other hand, referring to FIG. 4, a typical GaN crystal substrate 20p is a plurality of first stripe crystal regions in which a high dislocation density crystal region 20h extends in a stripe shape in the [1-100] direction. Although the deviation of the plane orientation between the central portion and the peripheral portion of the GaN crystal substrate in the direction parallel to the [1-100] direction can be reduced, the direction perpendicular to the [1-100] direction (that is, [11− 20] (direction parallel to the direction), it is not possible to reduce the deviation of the plane orientation between the central part and the peripheral part of the GaN crystal substrate.

In the GaN crystal substrate 20p of this embodiment, the width W ₁ of the first stripe crystal region 20hs of the high dislocation density crystal region 20h is preferably 5 μm or more and 120 μm or less, and more preferably 10 μm or more and 100 μm or less. When the width W _{1 of} the first stripe crystal region 20hs is smaller than 5 μm, the effect of collecting dislocations is reduced, and when the width W ₁ is larger than 120 μm, the low dislocation density crystal region 20k is decreased. The pitch P ₁ of the first stripe crystal region 20hs of the high dislocation density crystal region 20h is preferably 200 μm or more and 10,000 μm or less, and more preferably 400 μm or more and 9500 μm or less. When the pitch P _{1 of} the first stripe crystal region 20hs is smaller than 200 μm, each low dislocation density crystal region 20k is small, and when the pitch P ₁ is larger than 10,000 μm, the effect of collecting dislocations is reduced.

Further, the width W ₂ of the second stripe crystal region 20ht of the high dislocation density crystal region 20h is preferably 5 μm or more and 120 μm or less, and more preferably 10 μm or more and 100 μm or less. When the width W _{2 of} the second stripe crystal region 20ht is smaller than 5 μm, the effect of collecting dislocations is reduced, and when the width W ₂ is larger than 120 μm, the low dislocation density crystal region 20k is decreased. The pitch P ₂ of the second stripe crystal region 20ht of the high dislocation density crystal region 20h is preferably 200 μm or more and 10,000 μm or less, and more preferably 400 μm or more and 9500 μm or less. If the pitch P _{2 of} the second stripe crystal region 20ht is smaller than 200 μm, each low dislocation density crystal region 20k is small, and if it is larger than 10,000 μm, the effect of collecting dislocations is reduced.

  11 to 14, in the GaN crystal substrate 20p of the present embodiment, the main surface 20m is a small off angle (for example, larger than 0.05 ° and smaller than 1.0 ° with respect to the (0001) plane. From the viewpoint of growing the group III nitride semiconductor epitaxial layer 30 without forming the epitaxial abnormal growth region 30ei on the main surface 20m, the first stripe crystal region 20hs or the second stripe crystal. The region 20ht is preferably discontinuous at least at one place.

  Here, if the stripe crystal region in which at least one portion is discontinuous is either the first stripe crystal region 20hs or the second stripe crystal region 20ht, it extends in a direction perpendicular to the direction in which the off angle becomes larger. A stripe crystal region is preferred. In addition, even when the off-angles of the first stripe crystal region 20hs and the second stripe crystal region 20ht extend in the same direction, the second stripe crystal region 20ht and the first stripe crystal region 20h By making both of the crystal regions 20hs discontinuous at least at one place, the formation of the abnormal epitaxial growth region 30ei when the group III nitride semiconductor epitaxial layer 30 is grown can be suppressed.

  Referring to FIG. 13, main surface 20m has a small off angle (for example, 0. 0) in the [1-100] direction (for example, the direction in which first stripe crystal region 20hs extends) with respect to the (0001) plane. When the group III nitride semiconductor epitaxial layer 30 is grown on the main surface 20m of the GaN crystal substrate 20p having an off angle larger than 05 ° and smaller than 1.0 °, the low dislocation density crystal region 20k of the GaN crystal substrate 20p In the region immediately above, the region on the second stripe crystal region side having the larger off-angle among the two regions in contact with the second stripe crystal region 20ht extending in the [11-20] direction perpendicular to the [1-100] direction. An epitaxial abnormal growth region 30ei grown with the (0001) plane as the crystal growth surface is formed immediately above, and parallel to the main surface 20m immediately above the other regions. A region grown using a smooth surface (which is smaller than the (0001) surface but has an off angle) as a crystal growth surface is formed. A semiconductor device including such an abnormal epitaxial growth region 30ei has a reduced withstand voltage.

  Referring to FIG. 14, main surface 20m has a small off angle (for example, 0 °) with respect to (0001) plane, for example, in the [1-100] direction (this is the direction in which first stripe crystal region 20hs extends). Even in the case of a GaN crystal substrate 20p having a larger off angle than 0.7 °, the group III nitride semiconductor epitaxial layer 30 can be grown without forming the epitaxial abnormal growth region 30ei on the main surface 20m. it can.

Referring to FIG. 10, the length L _W of the discontinuous portion of the first stripe crystal region 20hs or the second stripe crystal region 20ht of the GaN crystal substrate 20p is not particularly limited, but is preferably 1 μm to 200 μm, and preferably 2 μm. More preferably, it is 100 μm or less. If the length L _W of the discontinuous portion is smaller than 1 μm, the abnormal epitaxial growth regions are connected to each other, and the epitaxial growth abnormalities are not alleviated. The length L of the continuous portion of the first stripe crystal region 20hs or the second stripe crystal region 20ht is not particularly limited, but is preferably 5 μm or more and 140 μm or less, and more preferably 10 μm or more and 40 μm or less. If the length L of the discontinuous portion is smaller than 5 μm, the dislocations that have been stored in the high dislocation density crystal region leak from the high dislocation density crystal region to the low dislocation density crystal region. The size is reduced and the size of each device obtained is reduced.

The carrier concentration of the GaN crystal substrate 20p of this embodiment is not particularly limited, but is preferably 1.00 × 10 ¹⁸ cm ⁻³ or more from the viewpoint of reducing the specific resistance of a semiconductor device including the GaN crystal substrate 20p. 0.0 × 10 ¹⁸ cm ⁻³ or more is more preferable. From the viewpoint of preventing the occurrence of cracks when manufacturing a GaN crystal substrate with a semiconductor epitaxial layer or a semiconductor device using the GaN crystal substrate 20p, the carrier concentration of the GaN crystal substrate 20p is 1.2 × 10 ¹⁹ cm. ⁻³ or less is preferable, and 1.0 × 10 ¹⁹ cm ⁻³ or less is more preferable. Here, the carrier concentration of the GaN crystal substrate can be measured by hole measurement.

  In the GaN crystal substrate 20p of this embodiment, the high dislocation density crystal region 20h is preferably a polarity inversion crystal region in which the polarity in the [0001] direction is inverted with respect to the low dislocation density crystal region 20k. When the high dislocation density crystal region 20h is a polarity inversion crystal region, dislocations are more easily collected in the high dislocation density crystal region 20h, and the dislocation density of the low dislocation density crystal region 20k is further reduced. Here, the polarity inversion region in which the polarity in the [0001] direction is inverted in the GaN crystal substrate 20p can be measured by the difference in etching property when the crystal surface is etched. That is, the (000-1) plane is a plane in which the polarity in the [0001] direction is reversed with respect to the (0001) plane, and is etched more easily than the (0001) plane. For example, when a GaN crystal substrate is immersed in an aqueous NaOH or KOH solution, the (000-1) plane that appears on the surface of the substrate is etched deeper than the (0001) plane that appears on the surface of the substrate.

  In the GaN crystal substrate 20p of the present embodiment, the low dislocation density crystal region 20k includes a (0001) plane growth crystal region 20kc and a facet growth crystal region 20kf, and the main surface 20m corresponds to the area of the facet growth crystal region 20kf. The area ratio of the (0001) plane growth crystal region 20kc (this ratio is referred to as the C / F ratio, hereinafter the same) is preferably 0.7 or less, more preferably 0.5 or less, and even more preferably 0.4 or less. .

  Here, as compared with the (0001) plane growth crystal region 20kc, the facet growth crystal region 20kf is likely to receive impurities such as O (oxygen), and its carrier concentration is increased, so that the specific resistance is low. Therefore, in a semiconductor device obtained by growing one or more group III nitride crystal layers on the GaN crystal substrate 20p, the lower the C / F ratio, the smaller the (0001) plane growth crystal region with a higher specific resistance. The on-resistance of the semiconductor device can be reduced, and a large current can be applied by the semiconductor device.

  The GaN crystal substrate 20p of the present embodiment includes a high dislocation density crystal including a plurality of first stripe crystal regions 20hs extending in the [1-100] direction and a plurality of second stripe crystal regions 20ht extending in the [11-20] direction. Since the region 20h is included, each low dislocation density crystal region 20k is surrounded on all sides by the high dislocation density crystal region 20h. For this reason, the (0001) plane growth crystal region 20kc is formed at the center of each low dislocation density crystal region 20k, and the facet growth crystal region 20kf is formed at the four peripheral portions, resulting in a low C / F ratio.

  Here, the (0001) plane grown crystal region 20kc refers to a crystal region grown using the (0001) plane as a crystal growth surface, and the facet grown crystal region 20kf refers to a crystal region grown using a facet as a crystal growth surface. Further, the high dislocation density crystal region 20h is a crystal region that has a polarity in the [0001] direction reversed with respect to the low dislocation density crystal region 20k, and has grown using the (000-1) plane as a crystal growth surface.

  On the other hand, referring to FIG. 4, a typical GaN crystal substrate 20p has a high dislocation density crystal region 20h composed of a plurality of first stripe crystal regions extending in the 1-100] direction. Each low dislocation density crystal region 20k is sandwiched between two sides by the density crystal region 20h. Therefore, a (0001) plane growth crystal region 20kc is formed at the center of each low dislocation density crystal region 20k, and a facet growth crystal region 20kf is formed at the two peripheral portions. That is, in the GaN crystal substrate of this embodiment, facet growth crystal regions are formed in the four peripheral portions of each low dislocation density crystal region, whereas in a typical GaN crystal substrate, each low dislocation density crystal region is formed. The facet growth crystal region is formed only in the two peripheral portions. For this reason, a typical GaN crystal substrate cannot make a C / F ratio as small as the GaN crystal substrate of this embodiment.

  The (0001) plane growth crystal region 20kc, the facet growth crystal region 20kf, and the high dislocation density crystal region 20h can be distinguished from each other by observing the main surface 20m of the GaN crystal substrate 20p with a fluorescence microscope. That is, when the main surface 20m of the GaN crystal substrate 20p is observed with a fluorescence microscope, the (0001) -plane-grown crystal region 20kc appears as the brightest first bright region, and the facet-grown crystal region 20kf appears as the darkest dark region. The density crystal region 20h appears as a bright second bright region next to the (0001) plane growth crystal region.

  Referring to FIG. 1, the GaN crystal substrate 20p of the present embodiment is not particularly limited, but 0.1 per dislocation density crystal region 20k is surrounded by the high dislocation density crystal region 20h. It is preferable to have 20 kd of dislocation concentrated regions / area to 5.5 / area. Low dislocation density of the GaN crystal substrate 20p When the density of the dislocation concentration region 20kd per region is larger than 5.5 / region, the withstand voltage characteristic of a semiconductor device manufactured using the GaN crystal substrate 20p The yield of the semiconductor device is reduced due to the reduction in the number of the semiconductor devices, and if the number is smaller than 0.1 / region, the ratio of the area of the (0001) plane growth crystal region 20kc to the area of the facet growth crystal region 20kf in the low dislocation density crystal region 20k / F ratio) increases, and the on-resistance of a semiconductor device manufactured using the GaN crystal substrate 20p increases.

Referring to FIG. 4, in GaN crystal substrate 20p having stripe-shaped high dislocation density crystal region 20h, a large number of dislocation concentration regions 20kd are observed in portions near low dislocation density crystal region 20h in low dislocation density crystal region 20k. . In particular, when the distance P ₁ -W ₁ between the stripe-shaped high dislocation density crystal regions is 400 μm or more, that is, when the width of the stripe-like low dislocation density crystal region 20 k is 400 μm or more, the density of the dislocation concentration region 20 kd increases. did.

On the other hand, referring to FIG. 1, a GaN crystal substrate 20p having a lattice-like high dislocation density crystal region 20h including a first stripe crystal region 20hs and a second stripe crystal region 20ht has a lattice-like high dislocation density. Even if the distances P ₁ -W ₁ and P ₂ -W ₂ between the crystal regions 20h are 400 μm or more, that is, the size of one region of the low dislocation density crystal region 20k surrounded by the high dislocation density crystal region 20h is small. Even when the size is 400 μm square (400 μm × 400 μm) or more, the density of the dislocation concentration region 20 kd observed in the low dislocation density crystal region is small, for example, 6 per region or less per one region of the low dislocation density crystal region 20 k. Preferably, it can be set to 0.1 piece / area or more and 5.5 piece / area or less.

(Embodiment 2)
With reference to FIGS. 1-3, one Embodiment of the manufacturing method of the GaN crystal substrate concerning this invention is a manufacturing method of the GaN crystal substrate of Embodiment 1, and comprises the following processes.

  With reference to FIG. 2, in the manufacturing method of the GaN crystal substrate of this embodiment, first, an off angle of 0 ° or more and 30 ° or less with respect to the plane orientation of the base substrate 10 corresponding to the (0001) plane of the GaN crystal substrate. A step of preparing a base substrate 10 having a main surface 10m having

  The underlying substrate 10 is not particularly limited as long as it can epitaxially grow a GaN crystal on the main surface 10 m, but is preferably a GaAs substrate, a sapphire substrate, a SiC substrate, or the like from the viewpoint of small crystal lattice mismatch. Used.

  Here, the plane orientation of the base substrate 10 corresponding to the (0001) plane of the GaN crystal substrate means the plane orientation of the base substrate 10 capable of growing a GaN crystal whose crystal growth plane is the (0001) plane. Depends on the type of base substrate 10. For example, when the base substrate 10 is a GaAs substrate having a cubic zinc blende crystal structure, the plane orientation is the (111) A plane, and the base substrate 10 is a hexagonal or rhombohedral corundum. In the case of a sapphire substrate having a type crystal structure, the plane orientation is the (0001) plane, and in the case where the base substrate 10 is a SiC substrate having a hexagonal wurtzite type crystal structure, the plane orientation is (0001). Surface. Further, since the main surface 10m of the base substrate 10 has an off angle of 0 ° or more and 30 ° or less with respect to the plane orientation, a GaN crystal having a (0001) plane as a crystal growth surface is grown thereon. Can be made.

  2 and 3, the GaN crystal substrate manufacturing method of the present embodiment then has a first surface corresponding to the [1-100] direction of the GaN crystal substrate 20p on the main surface 10m of the base substrate 10. Forming a mask 11 having a lattice pattern including a plurality of first stripe masks 11s extending in a direction and a plurality of second stripe masks 11t extending in a second direction corresponding to the [11-20] direction of the GaN crystal substrate 20p. The process of carrying out.

Here, the first direction corresponding to the [1-100] direction of the GaN crystal substrate 20p differs depending on the type of the base substrate 10, and is the [11-2] direction when the base substrate 10 is a GaAs substrate. When 10 is a sapphire substrate, the direction is [11-20], and when the base substrate 10 is a SiC substrate, the direction is [1-100]. The second direction corresponding to the [11-20] direction of the GaN crystal substrate 20p differs depending on the type of the base substrate 10, and is the [1-10] direction when the base substrate 10 is a GaAs substrate. When the substrate is a sapphire substrate, the direction is [1-100], and when the base substrate 10 is a SiC substrate, the direction is [11-20]. The mask 11 is not particularly limited as long as it is a material that suppresses the growth of GaN crystals, and SiO ₂ , Si ₃ N ₄ or the like is used. The method for forming the mask 11 is not particularly limited. For example, after the mask layer is formed by a sputtering method, the mask 11 having a lattice pattern can be formed by a photolithography method.

Further, the width W _M1 of the first stripe mask 11s in the mask 11 is preferably 5 μm or more and 120 μm or less, and more preferably 10 μm or more and 100 μm or less. When the width W _M1 of the first stripe mask 11s is smaller than 5 μm, the first stripe crystal region 20hs of the high dislocation density crystal region 20h may disappear during the growth of the GaN crystal 20, and the first stripe mask 11s grows when the width W _M1 is larger than 120 μm. The low dislocation density crystal region 20k of the GaN crystal 20 becomes small. The pitch P _M1 of the first stripe mask 11s in the mask 11 is preferably 200 μm or more and 10,000 μm or less, and more preferably 400 μm or more and 9500 μm or less. When the pitch P _M1 of the first stripe mask 11s is smaller than 200 μm, the low dislocation density crystal region 20k of each GaN crystal 20 to be grown is small, and when it is larger than 10,000 μm, the effect of collecting dislocations of the GaN crystal 20 to be grown is reduced. .

Further, the width W _M2 of the second stripe mask 11t in the mask 11 is preferably 5 μm or more and 120 μm or less, and more preferably 10 μm or more and 100 μm or less. If the width W _M2 of the second stripe mask 11t is smaller than 5 μm, the second stripe crystal region 20ht of the high dislocation density crystal region 20h may disappear when the GaN crystal 20 is grown, and if the width W _M2 is larger than 120 μm, the second stripe mask 11t is grown. The low dislocation density crystal region 20k of the GaN crystal 20 becomes small. The pitch P _M2 of the second stripe mask 11t in the mask 11 is preferably 200 μm or more and 10,000 μm or less, and more preferably 400 μm or more and 9500 μm or less. If the pitch P _M2 of the second stripe mask 11t is smaller than 200 μm, the low dislocation density crystal region 20k of each GaN crystal 20 to be grown becomes small, and if it is larger than 10,000 μm, the effect of collecting dislocations in the grown GaN crystal 20 is reduced. .

  2 and 3, the method for manufacturing a GaN crystal substrate according to this embodiment includes a step of growing GaN crystal 20 on main surface 10 m of base substrate 10 on which mask 11 is formed. The growth method of the GaN crystal 20 is not particularly limited, but from the viewpoint of increasing the crystal growth rate, a vapor phase method such as HVPE (hydride vapor phase epitaxy) or MOCVD (metal organic chemical vapor deposition) is preferable. Used.

  In the step of growing the GaN crystal 20, the GaN crystal 20 is grown on the mask 11 by (000-1) plane to form a polarity reversal crystal region, and the GaN crystal 20 is formed on the central portion of the opening 11 w of the mask 11 of the base substrate 10. The crystal 20 grows to a (0001) plane to form a (0001) plane grown crystal region 20kc, and the GaN crystal 20 is facet grown on the periphery of the opening 11w of the mask 11 to form a facet grown crystal region 20kf. .

  Here, (000-1) plane growth refers to growth using the (000-1) plane 20d as a crystal growth plane, and (0001) plane growth refers to growth using the (0001) plane 20c as a crystal growth plane. The facet growth means that the facet 20f is grown as a crystal growth surface. The facet 20f is a surface having an inclination with respect to the (0001) surface 20c.

  Here, the facet 20 f is formed on the periphery of the opening 11 w of the mask 11 because the mask 11 suppresses the growth of the GaN crystal 20, so that the growth of the GaN crystal 20 on the main surface 10 m of the base substrate 10. Is considered to start from the opening 11w of the mask 11 and the growth of the GaN crystal on the mask 11 is slower than the growth of the GaN crystal on the opening 11w.

  Further, at least the main surface 10 m of the base substrate 10 only needs to be exposed in the opening 11 w of the mask 11. For example, the main surface of the base substrate may be exposed on the entire surface of the opening of the mask 11, or the main surface of the base substrate may be exposed on a part of the surface of the opening of the mask.

  The method for exposing the main surface of the base substrate to a part of the mask opening is not particularly limited. For example, referring to FIGS. 7 and 8, a plurality of micro openings in the mask opening 11w. There is a method of forming an additional mask 12 having 12w. According to this method, the main surface of the base substrate is exposed in the micro opening 12w. The additional mask 12 formed here is for accelerating the facet growth during the growth of the GaN crystal, and the polarity inversion crystal region is not formed on the additional mask 12. By forming the additional mask 12, the dislocation density of the GaN crystal grown on the opening 11w of the mask can be further reduced.

Specifically, referring to FIG. 7, as an example of additional mask 12, hexagonal lattice-shaped additional mask 12 having a plurality of hexagonal micro openings 12 w can be cited. Although there is no restriction | limiting in particular in arrangement | positioning of the hexagonal-lattice-like micro opening part 12w, From a viewpoint of aiming at a uniform crystal growth, it arrange | positions so that it may become hexagonal dense on a plane. In particular, the width W _N of the additional mask 12 is preferably 0.5 μm or more and less than 5 μm. If the width W _N of the additional mask 12 is smaller than 0.5 μm, the effect of promoting facet growth is reduced. If the width W _N is 5 μm or more, a polarity inversion crystal region may be formed on the additional mask 12. The pitch P _N of the micro opening 12w is preferably 2.0μm or more 10μm or less. Pitch P _N of the micro opening 12w, since the greater the crystal nuclei formed in the early 2.0μm smaller crystal growth, a number of defects will occur than when those crystal nuclei are bonded to each other, 10 [mu] m If it is larger, the crystal nuclei formed at the beginning of crystal growth become larger, so stress is generated inside each crystal nucleus, and the orientation of the plane is likely to shift at the center and end of each crystal nucleus. When crystal nuclei grow and bond to each other, they are easily broken.

  Here, there is no restriction | limiting in particular in the directionality of arrangement | positioning of the hexagonal micro opening part 12w, For example, with reference to Fig.7 (a), mutually adjacent micro opening part 12w is made into 1st direction and 1st direction. Can be arranged side by side in a direction having an angle of 60 ° with respect to the direction. Further, referring to FIG. 7B, adjacent micro openings 12w can be arranged side by side in the second direction and in a direction having an angle of 60 ° with respect to the second direction. In the arrangement of the micro openings 12w shown in FIG. 7A, since the two sides of each micro opening are parallel to the second direction of the base substrate, the dislocation density is further reduced by promoting facet growth of the GaN crystal. From the viewpoint of making it preferable.

Referring to FIG. 8, another example of the additional mask is a stripe-shaped additional mask 12 having a plurality of stripe-shaped micro openings 12w. The arrangement of the stripe-shaped micro openings 12w is not particularly limited, but is preferably arranged periodically from the viewpoint of achieving uniform crystal growth. Here, the width W _N of the additional mask 12 is preferably 0.5 μm or more and less than 5 μm. If the width W _N of the additional mask 12 is smaller than 0.5 μm, the effect of promoting facet growth is reduced. If the width W _N is 5 μm or more, a polarity inversion crystal region may be formed on the additional mask 12. The pitch P _N of the micro opening 12w is preferably 2.0μm or more 10μm or less. Pitch P _N of the micro opening 12w, since the greater the crystal nuclei formed in the early 2.0μm smaller crystal growth, a number of defects will occur than when those crystal nuclei are bonded to each other, 10 [mu] m If it is larger, the crystal nuclei formed at the beginning of crystal growth become larger, so stress is generated inside each crystal nucleus, and the orientation of the plane is likely to shift at the center and end of each crystal nucleus. When crystal nuclei grow and bond to each other, they are easily broken.

  Here, referring to FIG. 8A, stripe-shaped micro openings 12w extending in the second direction adjacent to each other can be arranged in the first direction. Further, referring to FIG. 8B, stripe-shaped micro openings 12w extending in the first direction adjacent to each other can be arranged in the second direction.

7 and 8, the additional mask 12 is not particularly limited as long as it is a material that suppresses the growth of GaN crystals, and SiO ₂ , Si ₃ N ₄ or the like is used. The method for forming the additional mask 12 is not particularly limited. For example, after the mask layer is formed by a sputtering method, the additional mask 12 having a hexagonal lattice shape or a stripe pattern shape may be formed by a photolithography method. it can.

  In the GaN crystal grown on the mask opening 11w by the facet growth as described above, dislocations propagate from the center of the mask 11 to the periphery. For this reason, the dislocation density of the (0001) plane growth crystal region 20kc growing on the central portion of the opening 11w of the mask 11 and the facet growth crystal region 20kf growing on the peripheral portion of the opening 11w of the mask 11 is reduced. A low dislocation density crystal region 20k is formed. On the other hand, dislocations of the GaN crystal 20 are collected on the mask 11 to form a high dislocation density crystal region 20h.

Referring to FIG. 3, in the step of growing GaN crystal 20, first stripe crystal region 20 hs of high dislocation density crystal region 20 h is grown on first stripe mask 11 s of mask 11, and second stripe of mask 11 is grown. A second stripe crystal region 20ht of a high dislocation density crystal region 20h is grown on the mask 11t. Here, since the crystal growth rate of the high dislocation density crystal region 20h is smaller than the crystal growth rate of the low dislocation density crystal region 20k, the width W ₁ of the first stripe crystal region increases as the crystal growth thickness increases. smaller than the width W _M1 of one stripe mask width W ₂ of the second stripe-crystal region is smaller than the width W _M2 of the second stripe mask. Also, in certain crystal growth thickness, width W ₂ of the reduction rate 100 × the second stripe crystal region to the width W _M2 of the second stripe mask _{(W M2 -W 2) / W} M2 (%) is the first stripe The reduction rate of the width W ₁ of the first stripe crystal region with respect to the mask width W _M1 is smaller than 100 × (W _M1 −W ₁ ) / W _M1 (%).

  With reference to FIG. 3, the method for manufacturing a GaN crystal substrate according to the present embodiment includes a step of forming a main surface 20 m parallel to the main surface 10 m of the base substrate 10 on the GaN crystal 20. Through this process, the GaN crystal substrate 20p of the first embodiment is obtained from the GaN crystal 20. Here, the method of forming the main surface 20m parallel to the main surface 10m of the base substrate 10 on the GaN crystal 20 is not particularly limited, and a plurality of surfaces parallel to the main surface 10m of the base substrate 10 from the GaN crystal 20 can be used. Examples include a method of cutting and grinding and / or polishing the cut surface to form the main surface 20m, or a method of grinding and / or polishing the crystal growth surface of the GaN crystal 20 to form the main surface 20m.

  In the method for manufacturing a GaN crystal substrate of this embodiment, the first stripe mask 11s or the second stripe mask 11t formed on the main surface 10m of the base substrate 10 can be discontinuous at least at one location. By making the first stripe mask 11s discontinuous, a GaN crystal substrate 20p having a discontinuous first stripe crystal region 20hs is obtained (not shown). Further, by making the second stripe mask 11t discontinuous (see FIG. 11), a GaN crystal substrate 20p having a discontinuous second stripe crystal region 20ht is obtained (see FIG. 10).

  When producing a GaN crystal substrate having a main surface 20m having a small off angle (for example, an off angle of 0 ° to 0.7 °) with respect to the (0001) plane, an epitaxial abnormal growth region 30ei is formed on the main surface 20m. From the viewpoint of obtaining a GaN crystal substrate 20p on which a group III nitride semiconductor epitaxial layer can be grown without being formed, the first stripe mask 11s or the second stripe mask 11t formed on the main surface 10m of the base substrate 10 is The discontinuity is preferably at least at one location.

  Here, the mask 11 for discontinuous at least one portion is not particularly limited as long as it is either the first stripe mask 11s or the second stripe mask 11t, but the off-angle of the GaN crystal substrate 20p to be manufactured is not limited. A stripe mask extending in a direction corresponding to a direction perpendicular to the larger direction is preferable.

Referring to FIG. 11, the length L _MW of the discontinuous portion of first stripe mask 11s or second stripe mask 11t formed on main surface 10m of base substrate 10 is not particularly limited, but is 1 μm or more and 200 μm or less. Is preferably 2 μm or more and 100 μm or less. If the length L _MW of the discontinuous portion is smaller than 1 μm, each epitaxial abnormal growth region formed in the group III nitride semiconductor epitaxial layer grown on the GaN crystal substrate is connected, and the epitaxial growth abnormality is not alleviated, and 200 μm. If it is larger, the dislocation density of the GaN crystal substrate and the epitaxial layer will not be sufficiently reduced. The length L _M of the continuous portion of the first stripe mask 11s or the second stripe mask 11t is not particularly limited, but is preferably 5 μm or more and 140 μm or less, and more preferably 10 μm or more and 40 μm or less. If the length L _M of the discontinuous portion is smaller than 5 μm, the dislocations that have been stored in the high dislocation density crystal region of the GaN crystal substrate leak from the high dislocation density crystal region to the low dislocation density crystal region, and if it is larger than 140 μm, The size of the dislocation density crystal region is reduced, and the size of each device obtained is reduced.

In the growth of the GaN crystal 20, the first dislocation density crystal region 20hs of the high dislocation density crystal region 20h grown on the first stripe mask 11s and the first dislocation density crystal region 20h of the high dislocation density crystal region 20h grown on the second stripe mask 11t. The crystal growth rate of the two-stripe crystal region 20ht is lower than the crystal growth rate of the low dislocation density crystal region 20k grown on the base substrate 10. Therefore, the length L _W of the discontinuous portion of the first stripe crystal region 20hs or the second stripe crystal region 20ht of the GaN crystal substrate 20p is generally the discontinuity of the first stripe mask 11s or the second stripe mask 11t. The length of the part is less than L _MW . The length L of the continuous portion of the first stripe crystal region 20hs or the second stripe crystal region 20ht of the GaN crystal substrate 20p is generally the length of the continuous portion of the first stripe mask 11s or the second stripe mask 11t. L _M is less than or equal to.

(Embodiment 3)
Referring to FIG. 12, an embodiment of a GaN crystal substrate with a semiconductor epitaxial layer according to the present invention includes a GaN crystal substrate 20p of Embodiment 1 and at least one group III nitride formed on the GaN crystal substrate 20p. The group III nitride semiconductor epitaxial layer 30 includes a low dislocation density epitaxial crystal region 30k formed immediately above the low dislocation density crystal region 20k of the GaN crystal substrate 20p, and a GaN crystal substrate 20p. High dislocation density epitaxial crystal region 30h formed immediately above the high dislocation density crystal region 20h.

  The GaN crystal substrate 33 with a semiconductor epitaxial layer of the present embodiment has at least one group III nitride semiconductor epitaxial layer 30 grown immediately above the GaN crystal substrate 20p (upward direction substantially perpendicular to the main surface of the substrate). In order to take over the dislocation of the GaN crystal substrate 20p, a high dislocation density epitaxial crystal region 30h having a high dislocation density is formed immediately above the high dislocation density crystal region 20h of the GaN crystal substrate 20p, but the low dislocation of the GaN crystal substrate 20p is formed. A low dislocation density epitaxial crystal region 30k having a low dislocation density is formed immediately above the density crystal region 20k.

  The method for forming at least one group III nitride semiconductor epitaxial layer 30 on the GaN crystal substrate 20p is not particularly limited, but from the viewpoint that an epitaxial layer having good crystallinity for device use can be obtained relatively easily. The MOCVD method is preferable.

(Embodiment 4)
Referring to FIGS. 16 and 18, one embodiment of a semiconductor device according to the present invention is a GaN crystal substrate 20p according to the first embodiment and at least one formed on one main surface 20m of the GaN crystal substrate 20p. Group III nitride semiconductor epitaxial layers 30, 70 are formed on at least one of main surfaces 30m, 70m of group III nitride semiconductor epitaxial layers 30, 70 and the other main surface 20n of GaN crystal substrate 20p. The GaN crystal substrate 20p has a size of 400 μm square or more and a dislocation density of less than 1 × 10 ⁷ cm ⁻² . The method of forming at least one group III nitride semiconductor epitaxial layer 30 or 70 on one main surface 20m of the GaN crystal substrate 20p is not particularly limited, but an epitaxial layer with good crystallinity for device use is relatively From the viewpoint of being easily obtained, the MOCVD method or the like is preferably used. In addition, as a method for forming the electrodes 41, 42, 81, 82, an EB (electron beam) vapor deposition method, a resistance heating vapor deposition method, a sputter vapor deposition method, or the like is usually used.

In the semiconductor devices 40c and 80c formed into chips of the present embodiment, the GaN crystal substrate 20p included as a substrate has a size of 400 μm square or more, and dislocations are 1 × 10 ⁷ cm even when CL (cathode luminescence) observation is performed. A dislocation concentration region 20 kd concentrated locally above ⁻² is not observed, and the dislocation density crystal region 20 k having a dislocation density of less than 1 × 10 ⁷ cm ⁻² is formed. For this reason, the withstand voltage characteristics of the semiconductor devices 40c and 80c formed into chips are high.

  Referring to FIGS. 16 and 18, in semiconductor devices 40c and 80c of this embodiment, GaN crystal substrate 20p includes a (0001) plane growth crystal region 20kc and a facet growth crystal region 20kf. On one main surface 20m, the ratio of the area of the (0001) plane growth crystal region 20kc to the area of the facet growth crystal region 20kf (hereinafter also referred to as C / F ratio) is 0.2 or more and 0.7 or less. It is preferable that it is 0.2 or more and 0.5 or less.

  Compared with the (0001) plane growth crystal region 20kc, the facet growth crystal region 20kf is more likely to receive impurities such as O (oxygen) and has a higher carrier concentration, and therefore has a lower specific resistance. Therefore, the lower the C / F ratio, the lower the on-resistance of the semiconductor device, and the larger current can be applied to the semiconductor device. On the other hand, if the C / F is too low, it becomes difficult to push the dislocations in the low dislocation density crystal region 20k to the high dislocation density crystal region 20h, and it is difficult to reduce the dislocation density in the low dislocation density crystal region 20k.

The semiconductor devices 40c and 80c of the present embodiment include the following two specific examples. Referring to FIG. 16, a semiconductor device 40c as an example of this embodiment is an SBD (Schottky barrier diode). The semiconductor device 40c includes at least one group III nitride semiconductor epitaxial layer 30 on one main surface 20m of a GaN crystal substrate 20p having a size of 400 μm square or more and a dislocation density of less than 1 × 10 ⁷ cm ^−2. A GaN layer is formed. The GaN crystal substrate 20p is formed of only a low dislocation density crystal region 20k having a dislocation density of less than 1 × 10 ⁷ cm ⁻² . For this reason, the dislocation density of the low dislocation density epitaxial crystal region 30k of the group III nitride semiconductor epitaxial layer 30 formed on the low dislocation density crystal region 20k is less than 1 × 10 ⁷ cm ⁻² . The lower the dislocation density of the low dislocation density crystal region 20k and the low dislocation density epitaxial crystal region 30k, the better. For example, 1 × 10 ⁶ cm ⁻² or less is preferable. A first layer 41 a and a second layer 41 b are formed as the Schottky electrode 41 on the GaN layer (Group III nitride semiconductor epitaxial layer 30). An ohmic electrode 42 is formed on the other main surface 20n of the GaN crystal substrate 20p.

  In FIG. 16, the Schottky electrode 41 is formed so as to extend in a region immediately above two regions of the (0001) plane growth crystal region 20kc and the facet growth crystal region 20kf. It may be formed in a region immediately above the region 20kc.

Referring to FIG. 18, a semiconductor device 80c as another example of the present embodiment is an LED (light emitting diode). The semiconductor device 80c includes at least one group III nitride semiconductor epitaxial layer 70 on one main surface 20m of a GaN crystal substrate 20p having a size of 400 μm square or more and a dislocation density of less than 1 × 10 ⁷ cm ^−2. As shown, an n-type GaN layer 71, an n-type Al _0.1 Ga _0.9 N layer 72, a light emitting layer 73, a p-type Al _0.1 Ga _0.9 N layer 74, and a p-type GaN layer 75 are sequentially formed. The GaN crystal substrate 20p is formed of only a low dislocation density crystal region 20k having a dislocation density of less than 1 × 10 ⁷ cm ⁻² .

Therefore, the low dislocation density epitaxial crystal region 70k of the group III nitride semiconductor epitaxial layer 70 formed on the low dislocation density crystal region 20k (refer to FIG. 19 for details, the n-type GaN layer 71, n Dislocation density of the low dislocation density epitaxial crystal regions 71k, 72k, 73k, 74k, 75k) of the p-type Al _0.1 Ga _0.9 N layer 72, the light emitting layer 73, the p-type Al _0.1 Ga _0.9 N layer 74, and the p-type GaN layer 75) Is less than 1 × 10 ⁷ cm ⁻² . The lower the dislocation density of the low dislocation density crystal region 20k and the low dislocation density epitaxial crystal region 70k, the better. For example, 1 × 10 ⁶ cm ⁻² or less is preferable.

A p-side electrode 81 is formed on the p-type GaN layer 75. An n-side electrode 82 is formed on the other main surface 20n of the GaN crystal substrate 20p. The light emitting layer 73 may have a triple well structure MQW (multiple quantum well) structure in which, for example, a 15 nm thick GaN barrier layer and a 3 nm thick In _0.15 Ga _0.85 N well layer are alternately stacked.

  In FIG. 18, the p-side electrode 81 and the n-side electrode 82 are formed so as to extend to the regions immediately above and immediately below the two regions of the (0001) plane growth crystal region 20kc and the facet growth crystal region 20kf, respectively. However, they may be formed in regions immediately above and immediately below in the region of the (0001) plane growth crystal region 20kc, respectively.

(Embodiment 5)
Referring to FIGS. 15 to 19, one embodiment of a method for manufacturing a semiconductor device according to the present invention includes a step of preparing GaN crystal substrate 20 p of Embodiment 1, and at least one layer of III on GaN crystal substrate 20 p. A step of growing group nitride semiconductor epitaxial layers 30 and 70, and a main region of group III nitride semiconductor epitaxial layers 30 and 70 in regions immediately above and immediately below low dislocation density crystal region 20k of GaN crystal substrate 20p. Forming electrodes 41, 42, 81, 82 on at least one of the surfaces 30m, 70m and the other main surface 20n of the GaN crystal substrate 20p.

  By providing such a process, the obtained semiconductor devices 40, 40c, 80, 80c (wafer-like semiconductor devices 40, 80 and chip-shaped semiconductor devices 40c, 80c) are obtained by using the GaN crystal substrate 20p of the first embodiment, It includes at least one group III nitride semiconductor epitaxial layer 30 and 70 formed on GaN crystal substrate 20p. Here, the low dislocation density crystal region 20k of the GaN crystal substrate 20p of the first embodiment is 0.1 / region or more / 5.5 or less per region surrounded by the high dislocation density crystal region 20h. It has a dislocation concentration region. Further, at least one group III nitride semiconductor epitaxial layer 30, 70 formed on the GaN crystal substrate 20p is formed immediately above the high dislocation density crystal region 20h of the GaN crystal substrate 20p of the first embodiment. High dislocation density epitaxial crystal regions 30h and 70h having a high dislocation density, and low dislocation density epitaxial crystal regions 30k and 70k having a low dislocation density formed on the low dislocation density crystal region 20k of the GaN crystal substrate 20p. Further, it acts in the regions 40k and 80k immediately above and immediately below the low dislocation density crystal region 20k of the GaN crystal substrate 20p. For this reason, according to the manufacturing method of this embodiment, a semiconductor device having excellent device characteristics such as a high withstand voltage can be obtained with a high yield.

  In the semiconductor device manufacturing method of the present embodiment, the wafer-like semiconductor devices 40 and 80 are divided into the GaN crystal substrate 20p, the group III nitride semiconductor epitaxial layers 30 and 70, and the electrodes 41, 42, 81, and The wafer-like semiconductor devices 40 and 80 are divided by the dividing lines 40b and 80b so that 82 is contained in the regions 40k and 80k immediately above and below the low dislocation density crystal region 20k of the GaN crystal substrate 20p. Semiconductor devices 40c and 80c are obtained.

  The manufacturing method of the semiconductor devices 40, 40c, 80, 80c of the present embodiment includes the following two specific examples. With reference to FIG. 15 and FIG. 16, the manufacturing method of the semiconductor devices 40 and 40c as an example of this embodiment is a manufacturing method of SBD. This will be specifically described below.

First, the GaN crystal substrate 20p of Embodiment 1 is prepared by the manufacturing method of Embodiment 2 (GaN crystal substrate preparation step). Such a GaN crystal substrate 20p is preferable as the dislocation density in the low dislocation density crystal region 20k is low, and is preferably 1 × 10 ⁸ cm ⁻² or less, and more preferably 1 × 10 ⁶ cm ⁻² or less.

Next, for example, a GaN layer is grown as at least one group III nitride semiconductor epitaxial layer 30 on one main surface 20m of the GaN crystal substrate 20p (semiconductor epitaxial layer growth step). The growth method is not particularly limited, but the MOCVD (metal organic chemical vapor deposition) method or the like is preferable from the viewpoint that an epitaxial layer with good crystallinity for device use can be obtained relatively easily. The dislocation density of the GaN layer (group III nitride semiconductor epitaxial layer 30) thus obtained is preferably 1 × 10 in the low dislocation density epitaxial crystal region 30k formed on the low dislocation density crystal region 20k of the GaN crystal substrate 20p. It is less than ⁷ cm ⁻² and there is no dislocation concentration region, more preferably 1 × 10 ⁶ cm ⁻² or less.

  The GaN layer (group III nitride semiconductor epitaxial layer 30) formed on the GaN crystal substrate 20p thus obtained has a high dislocation density formed just above the high dislocation density crystal region 20h of the GaN crystal substrate 20p. It has a dislocation density epitaxial crystal region 30h and a low dislocation density epitaxial crystal region 30k having a low dislocation density formed on the low dislocation density crystal region 20k of the GaN crystal substrate 20p.

  Next, the ohmic electrode 42 is formed on the other main surface 20n of the GaN crystal substrate 20p (ohmic electrode forming step). Specifically, for example, the following steps are performed. First, the main surface 20n of the GaN crystal substrate 20p is cleaned with organic cleaning and hydrochloric acid. Thereafter, a layer of a metal material such as Ti, Al, Au or the like is formed on the entire main surface 20n by, for example, EB (electron beam) vapor deposition or resistance heating vapor deposition. Thereafter, for example, heat treatment is performed at 600 ° C. for about 2 minutes in a nitrogen atmosphere, and the metal material layer is alloyed to form the ohmic electrode 42.

  Next, Ni or Ni alloy is formed on the GaN layer (Group III nitride semiconductor epitaxial layer 30) in the region 40k immediately above and directly below the low dislocation density crystal region 20k of the GaN crystal substrate 20p. A Schottky electrode 41 including the first layer 41a is formed (Schottky electrode formation step). Here, in FIG. 15, the Schottky electrode 41 is formed so as to extend in a region immediately above the two regions of the (0001) plane growth crystal region 20 kc and the facet growth crystal region 20 kf. It may be formed in a region immediately above the crystal region 20kc. Specifically, for example, the following steps are performed. A circular opening located in a region 40k immediately above and below the low dislocation density crystal region 20k of the GaN crystal substrate 20p on the main surface 30m of the GaN layer (group III nitride semiconductor epitaxial layer 30) by photolithography. A resist having a portion is formed (not shown). Thereafter, the surface treatment of the GaN layer (group III nitride semiconductor epitaxial layer 30) by hydrochloric acid cleaning is performed at room temperature for 3 minutes. Next, a metal layer to be the Schottky electrode 41 is formed. First, a first metal layer made of Ni or Ni alloy to be the first layer 41a of the Schottky electrode 41 is formed, and is formed of Au to be the second layer 41b on the first metal layer. It is preferable to form a second metal layer. Such a metal layer can be formed by any method, for example, the first metal layer can be formed by the EB method, and the second metal layer can be formed by the resistance heating vapor deposition method. Thereafter, when the resist is removed, the metal layer formed on the resist is removed at the same time (lift-off), and a metal layer to be the Schottky electrode 41 is formed. Such a metal layer can be formed so that its planar shape is circular.

  Thereafter, the metal layer is heat-treated to obtain the Schottky electrode 41 including the first layer 41a. At this time, since the barrier height of the first layer 41a formed of Ni or Ni alloy can be increased, the barrier height of the Schottky electrode 41 is increased. The heat treatment of the metal layer is preferably performed at 300 ° C. or higher and 600 ° C. or lower, more preferably 400 ° C. or higher and 550 ° C. or lower, from the viewpoint of increasing the barrier height of the first layer 41a in a short time. In addition, materials, such as gold | metal | money, are mentioned as a 2nd metal layer which can raise the barrier height of the Schottky electrode 41 by the said heat processing. The heat treatment is preferably performed in an atmosphere containing nitrogen. Since N atoms are likely to transition at low energy, when heat is applied to the GaN layer (group III nitride semiconductor epitaxial layer 30), the N surface is exposed from the region exposed to the atmosphere for this heat treatment on the main surface 30m of the GaN layer. Atoms are easy to escape. However, when nitrogen is contained in the atmosphere to be heat-treated, N atoms are difficult to escape from the GaN layer, and the N atoms released from the GaN layer can be compensated. For this reason, N atoms which escape from the GaN layer can be suppressed. For this reason, even if heat treatment is performed, it is possible to suppress the formation of defects such as dislocations due to the loss of N atoms in the GaN layer. Therefore, an increase in reverse leakage current can be suppressed. In the heat treatment, the metal layer is preferably heat-treated in an atmosphere of atmospheric pressure. Note that the metal layer may be heat-treated in a pressurized atmosphere.

  In the step of forming the Schottky electrode 41, the formation of the metal layer and the heat treatment can be performed in parallel. Specifically, for example, a metal layer is formed on the main surface 30m of the GaN layer (group III nitride semiconductor epitaxial layer 30) and heated from the other main surface 20n side of the GaN crystal substrate 20p. Thereby, the metal layer formed on the main surface 30m of the GaN layer from the main surface 20n of the GaN crystal substrate 20p can be heat-treated. The method of heating from the main surface 20n side of the GaN crystal substrate 20p is not particularly limited. For example, a method of heating with a laser beam or the like, the main surface 20n side of the GaN crystal substrate 20p is mounted on the susceptor and attached to the susceptor. The method etc. which heat with heating members, such as a thermocouple, are mentioned. Note that the formation of the metal layer and the heat treatment are performed as long as at least a part of the steps can be performed simultaneously. In this way, a wafer-like SBD (wafer-like semiconductor device 40) is obtained which acts in the region 40k immediately above and directly below the low dislocation density crystal region 20k of the GaN crystal substrate 20p.

  Next, the wafer-like SBD (wafer-like semiconductor device 40) is made up of the GaN crystal substrate 20p, the group III nitride semiconductor epitaxial layer 30, the Schottky electrode 41, and the ohmic electrode 42 constituting each SBD. An SBD (chip) obtained by dividing the wafer-like SBD (wafer-like semiconductor device 40) by the dividing line 40b so as to be within the region 40k immediately above and below the 20p low dislocation density crystal region 20k. A semiconductor device 40c) is obtained.

  With reference to FIGS. 17 to 19, a method for manufacturing semiconductor devices 80 and 80 c as an example of the present embodiment is a method for manufacturing an LED. This will be specifically described below.

First, the GaN crystal substrate 20p of Embodiment 1 is prepared by the manufacturing method of Embodiment 2 (GaN crystal substrate preparation step). In such a GaN crystal substrate 20p, the lower the dislocation density of the low dislocation density crystal region 20k, the better. For example, it is preferably less than 1 × 10 ⁷ cm ^{−2 and} more preferably 1 × 10 ⁶ cm ⁻² or less.

Next, an n-type GaN layer 71, an n-type Al _0.1 Ga _0.9 N layer 72, a light emitting layer 73, as at least one group III nitride semiconductor epitaxial layer 70 on one main surface 20m of the GaN crystal substrate 20p. A p-type Al _0.1 Ga _0.9 N layer 74 and a p-type GaN layer 75 are sequentially grown (semiconductor epitaxial layer growth step). The growth method is not particularly limited, but the MOCVD (metal organic chemical vapor deposition) method or the like is preferable from the viewpoint that an epitaxial layer with good crystallinity for device use can be obtained relatively easily.

The at least one group III nitride semiconductor epitaxial layer 70 formed on the GaN crystal substrate 20p thus obtained has a high dislocation density formed immediately above the high dislocation density crystal region 20h of the GaN crystal substrate 20p. Dislocation density epitaxial crystal region 70h (specifically, referring to FIG. 19, n-type GaN layer 71, n-type Al _0.1 Ga _0.9 N layer 72, light-emitting layer 73, p-type Al _0.1 Ga _0.9 N layer 74 and p-type Low dislocation density epitaxial crystals formed on the high dislocation density epitaxial crystal regions 71h, 72h, 73h, 74h, and 75h) of the GaN layer 75 and the low dislocation density crystal regions 20k of the GaN crystal substrate 20p. region 70k (specifically, with reference to FIG. 19, n-type GaN layer 71, n-type Al _0.1 Ga _0.9 n layer 72, the light emitting layer 73, p-type with l _0.1 Ga _0.9 N layer 74 and the p-type GaN layer 75 of each of the low dislocation density epitaxial crystal regions 71k, 72k, 73k, 74k, and 75k), the.

  Next, in the region 80k immediately above and directly below the low dislocation density crystal region 20k of the GaN crystal substrate 20p, the p-side electrode is formed on the p-type GaN layer 75 (the uppermost layer of the group III nitride semiconductor epitaxial layer 70). 81 is formed (p-side electrode forming step). Next, an n-side electrode is formed on the other main surface 20n of the GaN crystal substrate 20p in the region 80k immediately above and directly below the low dislocation density crystal region 20k of the GaN crystal substrate 20p (n-side electrode forming step). ). Here, in FIG. 17, the p-side electrode 81 and the n-side electrode 82 are formed so as to extend to the regions immediately above and immediately below the two regions of the (0001) plane growth crystal region 20kc and the facet growth crystal region 20kf, respectively. However, they may be formed in regions immediately above and immediately below in the region of the (0001) plane growth crystal region 20kc, respectively. In this way, a wafer-like LED (wafer-like semiconductor device 80) is obtained which acts in the regions 40k and 80k immediately above and directly below the low dislocation density crystal region 20k of the GaN crystal substrate 20p.

  Next, in the wafer-like LED (wafer-like semiconductor device 80), the GaN crystal substrate 20p, the group III nitride semiconductor epitaxial layer 70, the p-side electrode 81, and the n-side electrode 82 constituting each LED are all GaN. LED formed by dividing a wafer-like LED (wafer-like semiconductor device 80) by a dividing line 80b so as to be within the region 80k immediately above and below the low dislocation density crystal region 20k of the crystal substrate 20p. A (chip semiconductor device 80c) is obtained.

[Example A]
First, as Example A, an example in which a GaN crystal substrate 20p is manufactured using a GaAs substrate or a sapphire substrate as the base substrate 10 will be described. Example A includes the following Examples A1 to A19 and Comparative Examples RA1 to RA3.

(Example A1)
1. 2. Preparation of Base Substrate With reference to FIG. 2, a GaAs substrate having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm was prepared as the base substrate 10 with the main surface 10 m being a (111) A plane.

2. 2. Formation of Mask Referring to FIG. 2, next, a SiO ₂ mask layer having a thickness of 0.1 μm is formed by sputtering on the main surface 10 m of the GaAs substrate (underlying substrate 10), and then by photolithography. An SiO ₂ mask 11 having a lattice pattern was formed. The SiO ₂ mask 11 includes a plurality of first stripe masks 11s extending in the [11-2] direction (first direction) of the GaSa substrate (base substrate 10) and a plurality extending in the [1-10] direction (second direction). The first stripe mask 11s has a width W _M1 of 40 μm and a pitch P _M1 of 400 μm, and the second stripe mask 11t has a width W _M2 of 40 μm and a pitch P _M2 of 400 μm. .

Simultaneously with the formation of the SiO ₂ mask 11, the micro openings 12 w adjacent to each other in the openings 11 w of the mask 11 as shown in FIG. 7A are [11-2] of the GaAs substrate (underlying substrate 10). An additional mask 12 in the form of a hexagonal lattice of SiO ₂ having a plurality of hexagonal micro openings 12w arranged in a direction (first direction) and a direction having an angle of 60 ° with respect to the first direction. Formed. Width W _N of the additional mask 12 is 2 [mu] m, the pitch P _N of the micro window 12w was 5 [mu] m.

3. 2. Growth of GaN crystal Referring to FIGS. 2 and 3, next, a thickness of GaAs substrate (underlying substrate 10) on the main surface 10m on which the SiO ₂ mask 11 and the additional SiO ₂ mask 12 are formed is increased by HVPE. A GaN buffer layer having a thickness of 60 nm was grown. The growth conditions of this buffer layer are as follows: the growth temperature is 490 ° C., the partial pressure of HCl gas that is brought into contact with the Ga melt to generate Ga chloride gas is 2 × 10 ⁻³ atm (0.2026 kPa), and Ga chloride gas. The partial pressure of NH ₃ gas that reacts with OH to generate GaN was 0.2 atm (20.26 kPa). Next, a GaN crystal having a thickness of 6 mm was grown on the GaN buffer layer by HVPE. The growth conditions of this GaN crystal are as follows: the growth temperature is 1030 ° C., the partial pressure of HCl gas that is brought into contact with Ga melt to generate Ga chloride gas is 2 × 10 ⁻² atm (2.026 kPa), Ga chloride gas. The partial pressure of the NH ₃ gas that reacts with OH to generate GaN was 0.3 atm (30.39 kPa). The partial pressure of O ₂ gas for doping O (oxygen) into the crystal was set to 0.0065 atm (659 Pa).

4). Fabrication of GaN Crystal Substrate Referring to FIG. 3, the obtained GaN crystal 20 is then sliced by a plurality of surfaces parallel to the main surface 10m of the GaAs substrate to obtain a plurality of GaN crystal substrates 20p having a thickness of 500 μm. It was.

When the dislocation density in an arbitrary low dislocation density crystal region is measured in the obtained plurality of GaN crystal substrates and the dislocation density is 1 × 10 ⁶ cm ⁻² or less, a good substrate is obtained from the GaN crystal. The number of sheets taken out was 5. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 1.02 × 10 ⁴ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained. Such dislocation density is measured using CL (cathode luminescence) mounted on an SEM (scanning electron microscope) for any low dislocation density crystal region and high dislocation density crystal region on the main surface of the GaN crystal substrate. The density was calculated by measuring the number of dislocations observed as dark spots in each region.

  Further, in the main surface of the GaN crystal substrate, the center point, the plane orientation at a point 20 mm away from the center point in the [1-100] direction, and a point 20 mm away from the center point in the [11-20] direction, It measured by the omega-rocking curve measurement regarding the (0002) plane of the GaN crystal by X-ray diffraction. The plane orientation at the center point of the main surface is (0001), and the deviation angle (first deviation angle) of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction is 0. The deviation angle (second deviation angle) of the surface orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the surface orientation at the center point is 0.06 °, and the surface orientation at the main surface The deviation angle was extremely small.

The carrier concentration of the GaN crystal substrate was 6.80 × 10 ¹⁸ cm ⁻³ according to hole measurement.

  Further, by observing the main surface of the GaN crystal substrate with a fluorescence microscope, the (0001) plane growth crystal region, the facet growth crystal region, and the high dislocation density crystal region in the main surface were identified. The ratio (C / F ratio) of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region calculated from the observation with the fluorescence microscope was 0.48, and the specific resistance of the entire substrate could be lowered. .

Referring to FIG. 3, when the first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 is observed with a fluorescence microscope, the pitch P ₁ is 400 μm and 1 mm from the crystal growth start surface 20b. The widths W _{1 on the} grown surface (growth thickness 1 mm surface, hereinafter the same) and 5.5 mm grown surface (growth thickness 5.5 mm surface, hereinafter the same) were 35.8 μm and 13.0 μm, respectively. . Further, when the second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 is observed with a fluorescence microscope, the pitch P ₂ is 400 μm, and the growth thickness is 1 mm and the growth thickness is 5.5 mm. The widths W ₂ were 39.0 μm and 26.0 μm, respectively. The results are summarized in Table 1.

(Example A2)
A base substrate similar to that in Example A1 was prepared, and a mask was formed in the same manner as in Example A1 except that the pitches P _M1 and P _M2 of the first and second stripe masks were set to 800 μm. A GaN crystal substrate was produced by growth.

The number of good substrates removed from the GaN crystal was 5. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 2.00 × 10 ⁴ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first (Shift angle) is 0.04 °, and the shift angle (second shift angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.07 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.40 × 10 ¹⁸ cm ⁻³ . Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.44, and the specific resistance of the entire substrate could be lowered.

The first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 800 μm and a width W ₁ of 35 mm on the growth thickness 1 mm surface and the growth thickness 5.5 mm surface. 8 μm and 13.0 μm. The second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 800 μm and a width W ₂ on the growth thickness of 1 mm plane and the growth thickness of 5.5 mm plane of 39. 0 μm and 26.0 μm. The results are summarized in Table 1.

(Example A3)
A base substrate similar to that in Example A1 was prepared, and the base substrate was prepared in the same manner as Example A1 except that the pitches P _M1 and P _M2 of the first and second stripe masks were 1500 μm, respectively. A GaN crystal substrate was formed by growing and growing a GaN crystal.

The number of good substrates removed from the GaN crystal was four. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 6.75 × 10 ⁴ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first Deviation angle) is 0.06 °, and the deviation angle (second deviation angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.11 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.55 × 10 ¹⁸ cm ⁻³ .
In addition, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate is 0.41, and the area of the (0001) plane growth crystal region is In comparison, the area of the facet growth crystal region was large.

The first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 1500 μm and a width W ₁ of 35 mm on the growth thickness 1 mm plane and the growth thickness 5.5 mm plane. 8 μm and 13.0 μm. The second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 1500 μm and a width W ₂ on the growth thickness of 1 mm plane and the growth thickness of 5.5 mm plane of 39. 0 μm and 26.0 μm. The results are summarized in Table 1.

(Example A4)
A base substrate similar to that in Example A1 was prepared, and a mask was formed in the same manner as in Example A1 except that the pitches P _M1 and P _M2 of the first and second stripe masks were 2000 μm, respectively. A GaN crystal substrate was produced by growth.

The number of good substrates removed from the GaN crystal was four. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 1.60 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first Deviation angle) is 0.06 °, and the deviation angle (second deviation angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.12 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.11 × 10 ¹⁸ cm ⁻³ . Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.39, and the specific resistance of the entire substrate could be lowered.

The first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 2000 μm and a width W ₁ of 35 mm on the growth thickness 1 mm surface and the growth thickness 5.5 mm surface. 8 μm and 13.0 μm. The second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 2000 μm and a width W ₂ of 39 mm on the growth thickness 1 mm plane and the growth thickness 5.5 mm plane, respectively. 0 μm and 26.0 μm. The results are summarized in Table 1.

(Example A5)
A base substrate similar to that in Example A1 was prepared, and a mask was formed in the same manner as in Example A1 except that the pitches P _M1 and P _M2 of the first and second stripe masks were set to 3000 μm, respectively. A GaN crystal substrate was produced by growth.

The number of good substrates removed from the GaN crystal was three. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 3.50 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first (Shift angle) is 0.07 °, and the shift angle (second shift angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.12 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.90 × 10 ¹⁸ cm ⁻³ . Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.35, and the specific resistance of the entire substrate could be lowered.

The first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P _{1 of} 3000 μm and a width W ₁ of 35 mm on the growth thickness 1 mm plane and the growth thickness 5.5 mm plane. 8 μm and 13.0 μm. Further, the second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a width W _{2 and a} pitch P _{2 of} 3000 μm on the growth thickness 1 mm surface and the 5.5 mm growth surface, respectively. 0 μm and 26.0 μm. The results are summarized in Table 1.

(Example A6)
A base substrate similar to that in Example A1 was prepared, and a mask was formed in the same manner as in Example A1 except that the pitches P _M1 and P _M2 of the first and second stripe masks were set to 4000 μm. A GaN crystal substrate was produced by growth.

The number of good substrates removed from the GaN crystal was three. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 5.50 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first Deviation angle) is 0.07 °, and the deviation angle (second deviation angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.13 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.43 × 10 ¹⁸ cm ⁻³ . Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.32, and the specific resistance of the entire substrate could be lowered.

The first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 4000 μm and a width W ₁ of 35 mm on the growth thickness 1 mm surface and 5.5 mm growth surface. 8 μm and 13.0 μm. Further, the second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 4000 μm, and a width W ₂ on the growth thickness of 1 mm and the growth thickness of 5.5 mm is 39. 0 μm and 26.0 μm. The results are summarized in Table 1.

(Example A7)
A base substrate similar to that in Example A1 was prepared, and a mask was formed in the same manner as in Example A1 except that the pitches P _M1 and P _M2 of the first and second stripe masks were set to 5000 μm. A GaN crystal substrate was produced by growth.

The number of good substrates taken from the GaN crystal was two. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 6.50 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first Deviation angle) is 0.07 °, and the deviation angle (second deviation angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.13 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.15 × 10 ¹⁸ cm ⁻³ . Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.29, and the specific resistance of the entire substrate could be lowered.

Further, the first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 5000 μm and a width W ₁ of 35 mm on the growth thickness 1 mm plane and the growth thickness 5.5 mm plane. 8 μm and 13.0 μm. Further, the second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 5000 μm and a width W ₂ of 39 mm on the growth thickness 1 mm plane and the growth thickness 5.5 mm plane, respectively. 0 μm and 26.0 μm. The results are summarized in Table 1.

(Example A8)
A base substrate similar to that in Example A1 was prepared, and a mask was formed in the same manner as in Example A1 except that the pitches P _M1 and P _M2 of the first and second stripe masks were 9500 μm, respectively. A GaN crystal substrate was produced by growth.

The number of good substrates taken from the GaN crystal was one. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 8.30 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively, for the GaN crystal substrate that is a good substrate. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first (Shift angle) is 0.09 °, and the shift angle (second shift angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.19 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.00 × 10 ¹⁸ cm ⁻³ . Further, the ratio (C / F ratio) of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region on the main surface of the GaN crystal substrate is 0.20, and the area of the (0001) plane growth crystal region is In comparison, the area of the facet growth crystal region was large.

The first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 9500 μm and a width W ₁ of 35 mm on the growth thickness 1 mm surface and 5.5 mm growth surface. 8 μm and 13.0 μm. The second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 9500 μm and a width W ₂ on the growth thickness of 1 mm plane and the growth thickness of 5.5 mm plane of 39. 0 μm and 26.0 μm. The results are summarized in Table 1.

(Example A9)
A base substrate similar to that in Example A1 was prepared, and a mask was formed in the same manner as Example A1 except that the pitches P _M1 and P _M2 of the first and second stripe masks were set to 10000 μm. A GaN crystal substrate was produced by growth.

The number of good substrates taken from the GaN crystal was one. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 8.80 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first Deviation angle) is 0.10 °, and the deviation angle (second deviation angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.20 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 5.25 × 10 ¹⁸ cm ⁻³ .

  In addition, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate is 0.18, and the area of the (0001) plane growth crystal region is In comparison, the area of the facet growth crystal region was large.

The first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P _{1 of} 10,000 μm and a width W ₁ of 35 mm on the growth thickness 1 mm plane and 5.5 mm growth plane. 8 μm and 13.0 μm. The second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P _{2 of} 10,000 μm and a width W ₂ on the growth thickness of 1 mm plane and the growth thickness of 5.5 mm plane of 39. 0 μm and 26.0 μm. The results are summarized in Table 1.

(Comparative Example RA1)
1. 5. Preparation of base substrate Referring to FIG. 5, a GaAs substrate having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm is prepared as the base substrate 10 as the base substrate 10 in the same manner as in Example A1. did.

2. Formation of Mask Referring to FIG. 5, next, a SiO ₂ mask layer having a thickness of 0.1 μm is formed by sputtering on the main surface 10 m of a GaAs substrate (underlying substrate 10), and then by photolithography. A SiO ₂ mask 11 having a stripe pattern was formed. The SiO ₂ mask 11 is a plurality of first stripe masks extending in the [11-2] direction (first direction) of the GaSa substrate (underlying substrate 10). The first stripe mask has a width W _M1 of 40 μm and a pitch P. _M1 was 400 μm.

At the same time as the formation of the SiO ₂ mask 11, the micro openings 12 w adjacent to each other in the openings 11 w of the mask 11 are arranged in the [11-2] direction (first order) of the GaSa substrate (underlying substrate 10) as shown in FIG. 1) and an additional mask 12 in the form of a hexagonal lattice of SiO ₂ having a plurality of hexagonal micro openings 12w arranged side by side in a direction having an angle of 60 ° with respect to the first direction. Width W _N of the additional mask 12 is 2 [mu] m, the pitch P _N of the micro window 12w was 5 [mu] m.

3. Growth of GaN Crystal Referring to FIGS. 5 and 6, next, as in Example A1, main surface 10m on which a SiO ₂ mask 11 of GaAs substrate (underlying substrate 10) and additional mask 12 of SiO ₂ are formed. A GaN buffer layer having a thickness of 60 nm was grown on the HVPE method, and then a GaN crystal having a thickness of 6 mm was grown.

4). Fabrication of GaN Crystal Substrate Referring to FIG. 6, next, similarly to Example A1, the obtained GaN crystal 20 is sliced by a plurality of planes parallel to the main surface 10m of the GaAs substrate, and a plurality of 500 μm thick A GaN crystal substrate 20p was obtained.

The number of good substrates removed from the GaN crystal was 5. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 3.15 × 10 ⁴ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first Deviation angle) is 0.04 °, and the deviation angle (second deviation angle) of the plane orientation at a point 20 mm away in the [11-20] direction from the central point with respect to the plane orientation at the central point is 0.14. The deviation angle of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.28 × 10 ¹⁸ cm ⁻³ .

  Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 1.33, and the specific resistance of the entire substrate was high.

The first stripe crystal region, which is the high dislocation density crystal region 20h of the GaN crystal 20, has a pitch P ₁ of 400 μm and a width W ₁ of 35 mm on the growth thickness 1 mm surface and the growth thickness 5.5 mm surface. 8 μm and 13.0 μm. The results are summarized in Table 1.

(Comparative Example RA2)
A base substrate similar to that in Comparative Example RA1 was prepared, and a mask was formed in the same manner as in Comparative Example RA1 except that the pitch P _M12 of the first stripe mask was set to 5000 μm, and a GaN crystal was grown. Was made.

The number of good substrates removed from the GaN crystal was zero. Regarding the fabricated GaN crystal substrate, the average dislocation density in the low dislocation density crystal region and the high dislocation density crystal region is 2.11 × 10 ⁷ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. The dislocation density also increased in the dislocation density crystal region.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first (Shift angle) is 0.11 °, and the shift angle (second shift angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.34 °. In the [11-20] direction, the deviation angle of the plane orientation was large. The carrier concentration of the GaN crystal substrate was 6.30 × 10 ¹⁸ cm ⁻³ .

  Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.80, and the specific resistance of the entire substrate was high.

The first stripe crystal region, which is the high dislocation density crystal region 20h of the GaN crystal 20, has a pitch P ₁ of 5000 μm and a width W ₁ of 35 mm on the growth thickness 1 mm plane and the growth thickness 5.5 mm plane. 8 μm and 13.0 μm. The results are summarized in Table 1.

(Comparative Example RA3)
A base substrate similar to that in comparative example RA1 was prepared, and a mask was formed in the same manner as in comparative example RA1 except that the pitch P _M12 of the first stripe mask was set to 10000 μm. Was made.

The number of good substrates removed from the GaN crystal was zero. For the fabricated GaN crystal substrate, the average dislocation density in the low dislocation density crystal region and the high dislocation density crystal region is 7.89 × 10 ⁷ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. The dislocation density also increased in the dislocation density crystal region.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first Deviation angle) is 0.20 °, and the deviation angle (second deviation angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.38 °. In the [11-20] direction, the deviation angle of the plane orientation was large. The carrier concentration of the GaN crystal substrate was 6.10 × 10 ¹⁸ cm ⁻³ .

  Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.55, and the specific resistance of the entire substrate could be lowered.

The first stripe crystal region, which is the high dislocation density crystal region 20h of the GaN crystal 20, has a pitch P ₁ of 10,000 μm and a width W ₁ of 35 mm on the growth thickness 1 mm surface and the growth thickness 5.5 mm surface. 8 μm and 13.0 μm. The results are summarized in Table 1.

Referring to Table 1, the following was found from the results of Comparative Examples RA1 to RA3 and Examples A1 to A9. A typical GaN crystal substrate including a stripe-shaped high dislocation density crystal region (first stripe crystal region) extending in the [1-100] direction on the main surface has a pitch P ₁ of the first stripe crystal region of 400 μm, 5000 μm, As the size increases to 10,000 μm, the concentration of dislocations in the high dislocation density crystal region is remarkably reduced, and the dislocation densities in the low dislocation density crystal region are 3.15 × 10 ⁴ cm ⁻² and 2.11 × 10 ⁷ cm, respectively. ⁻² and 7.89 × 10 ⁷ cm ^−2, and the number of good substrates obtained was 5, 0, and 0, respectively (Comparative Examples RA1 to RA3). On the other hand, the present invention includes a lattice-shaped high dislocation density crystal region including a first stripe crystal region extending in the [1-100] direction and a second stripe crystal region extending in the [11-20] direction on the main surface. In the GaN crystal substrate, even when the pitches P ₁ and P _{2 of} the first and second stripe crystals are increased to 400 μm, 5000 μm, and 10000 μm, respectively, the concentration of dislocations in the high dislocation density crystal region is hardly reduced. Five, two, and one good substrate can be taken, and the dislocation density in the low dislocation density crystal region in the good substrate is 1.02 × 10 ⁴ cm ⁻² , 6.50 × 10 ⁵ cm ⁻² , and 8.80, respectively. × 10 ⁵ cm ⁻² was small (Examples A1, A7 and A9).

A typical GaN crystal substrate having a stripe-shaped high dislocation density crystal region (first stripe width W ₁ is 40 μm, pitch P ₁ is 5000 μm) extending in the [1-100] direction on the main surface is [1 The deviation angle (first deviation angle) of the main surface in the −100] direction was as small as 0.11 °, but the deviation angle (second deviation angle) of the main surface in the [11-20] direction was 0.34 °. It was large (Comparative Example RA2). On the other hand, lattice-like high dislocation density crystal regions extending in the [1-100] direction and [11-20] direction on the main surface (the widths W ₁ and W _{2 of} the first and second stripes are 40 μm and the pitch, respectively) In the GaN crystal substrate according to the present invention having P ₁ and P ₂ of 5000 μm, respectively, the deviation angle of the main surface in the [1-100] direction and the [11-20] direction is as small as 0.07 and 0.13, respectively. (Example A7).

Further, a typical GaN crystal substrate having a stripe-shaped high dislocation density crystal region (first stripe width W ₁ is 40 μm, pitch P ₁ is 5000 μm) extending in the [1-100] direction on the main surface is The ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) was as large as 0.80. On the other hand, lattice-like high dislocation density crystal regions extending in the [1-100] direction and [11-20] direction on the main surface (the widths W ₁ and W _{2 of} the first and second stripes are 40 μm and the pitch, respectively) The GaN crystal substrate according to the present invention having P ₁ and P ₂ of 5000 μm was able to reduce the C / F ratio to 0.29 (Example A7). Thereby, the semiconductor device using the GaN crystal substrate according to the present invention is expected to have low on-resistance.

In any of Examples A1 to A9, the width W _{1 of} the first stripe crystal region (high dislocation density crystal region extending in the [1-100] direction) (35.8 μm at a growth thickness of 1 mm, growth thickness) The length of 13.0 μm at 5.5 mm is smaller than the width W _M1 (40 μm) of the first stripe mask (a mask extending in the [1-100] direction), and the second stripe crystal region ([11-20] direction). The width W ₂ (39.0 μm at the growth thickness of 1 mm and 26.0 μm at the growth thickness of 5.5 mm) of the high dislocation density crystal region extending in the direction of the second stripe mask (mask extending in the [11-20] direction) is It was smaller than the width W _M2 (40 μm).

Furthermore, when the growth thickness of the GaN crystal is 1 mm, the reduction rate 2.5% of the width W ₂ (39.0 μm) of the second stripe crystal region with respect to the width W _M2 (40 μm) of the second stripe mask is 2.5%. The reduction rate of the width W ₁ (35.8 μm) of the first stripe crystal region with respect to the width W _M1 (40 μm) was smaller than 10.5%. In addition, when the growth thickness of the GaN crystal is 5.5 mm, the reduction rate 35.0% of the width W ₂ (26.0 μm) of the second stripe crystal region with respect to the width W _M2 (40 μm) of the second stripe mask is the first stripe. The reduction rate of the width W ₁ (13.0 μm) of the first stripe crystal region with respect to the mask width W _M1 (40 μm) was smaller than 67.5%.

(Example A10)
A base substrate similar to that in Example A4 was prepared, and a mask was formed in the same manner as in Example A4, except that the widths W _M1 and W _M2 of the first and second stripe masks were 10 μm, respectively. A GaN crystal substrate was produced by growth.

The number of good substrates removed from the GaN crystal was four. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 2.00 × 10 ⁵ cm ⁻² and 8.35 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first Deviation angle) is 0.06 °, and the deviation angle (second deviation angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.12 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.19 × 10 ¹⁸ cm ⁻³ .

  In addition, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.36, and the specific resistance of the entire substrate could be reduced.

Further, the first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 2000 μm and a width W ₁ on the growth thickness of 1 mm plane and the growth thickness of 5.5 mm plane of 9. 0 μm and 3.3 μm. Further, the second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 2000 μm, and a width W ₂ on the growth thickness of 1 mm plane and the growth thickness of 5.5 mm plane is 9. 8 μm and 6.5 μm. The results are summarized in Table 2.

(Example A11)
A base substrate similar to that in Example A4 was prepared, and a mask was formed in the same manner as in Example A4, except that the widths W _M1 and W _M2 of the first and second stripe masks were 100 μm, respectively. A GaN crystal substrate was produced by growth.

The number of good substrates removed from the GaN crystal was four. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 1.20 × 10 ⁵ cm ⁻² and 7.90 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first Deviation angle) is 0.05 °, and the deviation angle (second deviation angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.10 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.01 × 10 ¹⁸ cm ⁻³ .

  Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.37, and the specific resistance of the entire substrate could be lowered.

Further, the first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 2000 μm and a width W ₁ on the growth thickness of 1 mm plane and the growth thickness of 5.5 mm plane of 89.mu.m, respectively. 5 μm and 32.5 μm. Further, the second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 2000 μm and a width W ₂ of 97 mm on the growth thickness 1 mm plane and the growth thickness 5.5 mm plane. 5 μm and 65.0 μm. The results are summarized in Table 2.

(Example A12)
A base substrate similar to that in Example A4 was prepared except that the main surface had an off angle of 10 ° in the [1-10] direction from the (111) A surface, and a mask was formed in the same manner as in Example A4. A GaN crystal was grown to produce a GaN crystal substrate.

The number of good substrates removed from the GaN crystal was four. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 1.88 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the central point of the main surface of these GaN crystal substrates is a plane orientation having an off angle of 10 ° in the (0001) to [11-20] direction, and [1- The deviation angle (first deviation angle) of the plane orientation at a point 20 mm away in the [100] direction is 0.03 °, and the plane at a point 20 mm away from the center point with respect to the plane orientation at the center point in the [11-20] direction. The azimuth shift angle (second shift angle) was 0.05 °, and the plane azimuth shift angle on the principal surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.50 × 10 ¹⁸ cm ⁻³ .

  Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.50, and the specific resistance of the entire substrate could be lowered.

Further, the first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 2000 μm and a width W ₁ of 34 mm on the growth thickness 1 mm plane and 5.5 mm growth plane. 5 μm and 11.8 μm. Further, the second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 2000 μm and a width W ₂ of 37 mm on the growth thickness 1 mm surface and the growth thickness 5.5 mm surface, respectively. 1 μm and 25.6 μm. The results are summarized in Table 2.

(Example A13)
A base substrate similar to that in Example A4 is prepared except that the main surface has an off angle of 25 ° in the [1-10] direction from the (111) A surface, and a mask is formed in the same manner as in Example A4. A GaN crystal was grown to produce a GaN crystal substrate.

The number of good substrates removed from the GaN crystal was four. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 2.10 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the central point of the main surface of these GaN crystal substrates is a plane orientation having an off angle of 25 ° from the (0001) to the [11-20] direction, and [1- The deviation angle (first deviation angle) of the plane orientation at a point 20 mm away in the [100] direction is 0.07 °, and the plane at a point 20 mm away from the center point with respect to the plane orientation at the center point in the [11-20] direction. The azimuth shift angle (second shift angle) was 0.10 °, and the plane azimuth shift angle on the principal surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.23 × 10 ¹⁸ cm ⁻³ .

  Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.23, and the specific resistance of the entire substrate could be lowered.

Further, the first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 2000 μm and a width W ₁ of 33 mm on the growth thickness 1 mm plane and the growth thickness 5.5 mm plane. 2 μm and 10.9 μm. The second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 2000 μm and a width W ₂ of 35 mm on the growth thickness 1 mm surface and the growth thickness 5.5 mm surface. 2 μm and 23.2 μm. The results are summarized in Table 2.

(Example A14)
A base substrate similar to that in Example A4 was prepared except that the main surface had an off angle of 10 ° in the [11-2] direction from the (111) A surface, and a mask was formed in the same manner as in Example A4. A GaN crystal was grown to produce a GaN crystal substrate.

The number of good substrates removed from the GaN crystal was four. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 1.98 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the central point of the main surface of these GaN crystal substrates is a plane orientation having an off angle of 10 ° in the (0001) to [11-20] direction, and [1- The deviation angle (first deviation angle) of the plane orientation at a point 20 mm away in the [100] direction is 0.03 °, and the plane at a point 20 mm away from the center point with respect to the plane orientation at the center point in the [11-20] direction. The azimuth shift angle (second shift angle) was 0.05 °, and the plane azimuth shift angle on the principal surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.30 × 10 ¹⁸ cm ⁻³ .

  Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.48, and the specific resistance of the entire substrate could be lowered.

The first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal has a pitch P ₁ of 2000 μm and a width W ₁ of 34.5 μm on the growth thickness 1 mm surface and the growth thickness 5.5 mm surface. And 11.8 μm. The second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 2000 μm, and the width W ₂ on the growth thickness 1 mm surface and the growth thickness 5.5 mm surface is 37 respectively. 0.1 μm and 25.6 μm. The results are summarized in Table 2.

(Example A15)
A base substrate similar to that in Example A4 is prepared except that the main surface has an off angle of 25 ° in the [11-2] direction from the (111) A surface, and a mask is formed in the same manner as in Example A4. A GaN crystal was grown to produce a GaN crystal substrate.

The number of good substrates removed from the GaN crystal was four. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 2.30 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the central point of the main surface of these GaN crystal substrates is a plane orientation having an off angle of 25 ° from the (0001) to the [11-20] direction, and [1- The deviation angle (first deviation angle) of the plane orientation at a point 20 mm away in the [100] direction is 0.07 °, and the plane at a point 20 mm away from the center point with respect to the plane orientation at the center point in the [11-20] direction. The azimuth shift angle (second shift angle) was 0.10 °, and the plane azimuth shift angle on the principal surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.03 × 10 ¹⁸ cm ⁻³ .

  Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.20, and the specific resistance of the entire substrate could be lowered.

Further, the first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 2000 μm and a width W ₁ of 33 mm on the growth thickness 1 mm plane and the growth thickness 5.5 mm plane. 2 μm and 10.9 μm. The second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 2000 μm and a width W ₂ of 35 mm on the growth thickness 1 mm surface and the growth thickness 5.5 mm surface. 2 μm and 23.2 μm. The results are summarized in Table 2.

(Example A16)
1. 2. Preparation of Base Substrate With reference to FIG. 2, a sapphire substrate having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm was prepared as the base substrate 10 with the main surface 10 m being a (0001) plane.

2. 2. Formation of Mask Referring to FIG. 2, next, a SiO ₂ mask layer having a thickness of 0.1 μm is formed by sputtering on the main surface 10m of the sapphire substrate (underlying substrate 10), and then by photolithography. An SiO ₂ mask 11 having a lattice pattern was formed. The SiO ₂ mask 11 includes a plurality of first stripe masks 11s extending in the [11-20] direction (first direction) and a plurality extending in the [1-100] direction (second direction) of the sapphire substrate (underlying substrate 10). The first stripe mask 11s has a width W _M1 of 40 μm and a pitch P _M1 of 400 μm, and the second stripe mask 11t has a width W _M2 of 40 μm and a pitch P _M2 of 400 μm. .

Simultaneously with the formation of the SiO ₂ mask 11, the micro openings 12 w adjacent to each other in the openings 11 w of the mask 11 are arranged in the [11-20] direction (first order) of the sapphire substrate (underlying substrate 10) as shown in FIG. 1) and an additional mask 12 in the form of a hexagonal lattice of SiO ₂ having a plurality of hexagonal micro openings 12w arranged side by side in a direction having an angle of 60 ° with respect to the first direction. Width W _N of the additional mask 12 is 2 [mu] m, the pitch P _N of the micro window 12w was 5 [mu] m.

3. Growth of GaN Crystal Referring to FIGS. 2 and 3, next, on the main surface 10m of the sapphire substrate (underlying substrate 10) on which the SiO ₂ mask 11 is formed, as in Example A1, the HVPE method is used. A GaN buffer layer having a thickness of 60 nm was grown, and then a GaN crystal having a thickness of 6 mm was grown.

4). Fabrication of GaN Crystal Substrate Referring to FIG. 3, next, similarly to Example A1, the obtained GaN crystal 20 is sliced by a plurality of surfaces parallel to the main surface 10m of the GaAs substrate, and a plurality of 500 μm thick A GaN crystal substrate 20p was obtained.

The number of good substrates removed from the GaN crystal was 5. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 1.01 × 10 ⁴ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first (Shift angle) is 0.03 °, and the shift angle (second shift angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.05 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.99 × 10 ¹⁸ cm ⁻³ .

  Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.52, and the specific resistance of the entire substrate could be reduced.

The first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 400 μm and a width W ₁ of 35 mm on the growth thickness 1 mm plane and the growth thickness 5.5 mm plane. 8 μm and 13.0 μm. Further, the second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 400 μm and a width W ₂ on the growth thickness of 1 mm plane and the growth thickness of 5.5 mm plane of 39. 0 μm and 26.0 μm. The results are summarized in Table 2.

(Example A17)
A base substrate similar to that in Example A16 was prepared, and a mask was formed in the same manner as in Example A16, except that the pitches P _M1 and P _M2 of the first and second stripe masks were set to 5000 μm. A GaN crystal substrate was produced by growth.

The number of good substrates taken from the GaN crystal was two. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 4.50 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first Deviation angle) is 0.07 °, and the deviation angle (second deviation angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.10 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.25 × 10 ¹⁸ cm ⁻³ .

  Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.25, and the specific resistance of the entire substrate could be lowered.

Further, the first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₁ of 5000 μm and a width W ₁ of 35 mm on the growth thickness 1 mm plane and the growth thickness 5.5 mm plane. 8 μm and 13.0 μm. Further, the second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P ₂ of 5000 μm and a width W ₂ of 39 mm on the growth thickness 1 mm plane and the growth thickness 5.5 mm plane, respectively. 0 μm and 26.0 μm. The results are summarized in Table 2.

(Example A18)
A base substrate similar to that in Example A16 was prepared, and a mask was formed in the same manner as in Example A16, except that the pitches P _M1 and P _M2 of the first and second stripe masks were 10000 μm. A GaN crystal substrate was produced by growth.

The number of good substrates taken from the GaN crystal was one. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 8.20 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first (Shift angle) is 0.08 °, and the shift angle (second shift angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.15 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.25 × 10 ¹⁸ cm ⁻³ .

  Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.25, and the specific resistance of the entire substrate could be lowered.

The first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P _{1 of} 10,000 μm and a width W ₁ of 35 mm on the growth thickness 1 mm plane and 5.5 mm growth plane. 8 μm and 13.0 μm. Further, the second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal 20 has a pitch P _{1 of} 10,000 μm, and a width W ₂ on the growth thickness of 1 mm and the growth thickness of 5.5 mm is 39. 0 μm and 26.0 μm. The results are summarized in Table 2.

(Example A19)
A base substrate similar to Example A1 is prepared except that the diameter is 4 inches (101.6 mm), a mask is formed in the same manner as Example A1, a GaN crystal is grown, and a GaN crystal substrate is formed. Produced.

The number of good substrates removed from the GaN crystal was 5. The average dislocation density of the low dislocation density crystal region and the high dislocation density crystal region is 1.02 × 10 ⁴ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² for the GaN crystal substrate that is a good substrate, respectively. A GaN crystal substrate having a crystal region with an extremely low dislocation density was obtained.

The plane orientation at the center point of the main surface of these GaN crystal substrates is (0001), and the deviation angle of the plane orientation at the point 20 mm away from the center point with respect to the plane orientation at the center point in the [1-100] direction (first (Shift angle) is 0.03 °, and the shift angle (second shift angle) of the plane orientation at a point 20 mm away from the center point in the [11-20] direction with respect to the plane orientation at the center point is 0.05 °. The angle of deviation of the plane orientation on the main surface was extremely small. The carrier concentration of the GaN crystal substrate was 6.80 × 10 ¹⁸ cm ⁻³ .

  Further, the ratio of the area of the (0001) plane growth crystal region to the area of the facet growth crystal region (C / F ratio) on the main surface of the GaN crystal substrate was 0.51, and the specific resistance of the entire substrate could be lowered.

The first stripe crystal region 20hs of the high dislocation density crystal region 20h of the GaN crystal has a pitch P ₁ of 400 μm and a width W ₁ of 35.8 μm on the growth thickness 1 mm surface and the growth thickness 5.5 mm surface, respectively. And 13.0 μm. The second stripe crystal region 20ht of the high dislocation density crystal region 20h of the GaN crystal has a pitch P ₂ of 400 μm and a width W ₂ of 39.0 μm on the growth thickness 1 mm surface and the growth thickness 5.5 mm surface, respectively. And 26.0 μm. The results are summarized in Table 2.

With reference to Table 2, the following was found from the results of Examples A10 to A19. Even if both the widths W _M1 and W _M2 of the first and second stripe masks of the lattice-shaped mask formed on the main surface on the base substrate are 10 μm or 100 μm, the dislocation density in the low dislocation density crystal region is 2 A GaN crystal substrate of the present invention as low as 0.000 × 10 ⁵ cm ⁻² or 1.20 × 10 ⁵ cm ⁻² was obtained (Examples A10 and A11).

  In addition, the main substrate has an off angle of 10 ° or 25 ° with respect to the plane orientation of the base substrate corresponding to the (0001) plane of the GaN crystal substrate to be manufactured ((111) A when the base substrate is a GaAs substrate). By using a base substrate having a plane, the GaN crystal substrate of the present invention can be obtained in which the main surface has an off angle of 10 ° or 25 ° with respect to the (0001) plane and the dislocation density in the low dislocation density crystal region is low. (Examples A12 to A15).

  Further, even when a sapphire substrate was used as the base substrate, the GaN crystal substrate of the present invention having a low dislocation density in the low dislocation density crystal region was obtained (Examples A16 to A18). Further, even when a GaAs substrate having a diameter of 4 inches (101.6 mm) was used as the base substrate, the GaN crystal substrate of the present invention having a low dislocation density in the low dislocation density crystal region was obtained (Example A19).

[Example B]
Next, referring to FIG. 15 and FIG. 16 as Example B, a group III nitride semiconductor epitaxial layer 30 is grown on the main surface 20m of the GaN crystal substrate 20p to form a GaN crystal substrate with a semiconductor epitaxial layer. Further, a Schottky electrode 41 is formed on the main surface 30m of the group III nitride semiconductor epitaxial layer 30, and an ohmic electrode 42 is formed on the main surface 20n of the GaN crystal substrate 20p to manufacture SBDs as the semiconductor devices 40 and 40c. The embodiment will be described. Example B includes the following Examples B1 to B24 and Comparative Examples RB1 to RB3.

(Example B1)
1. Preparation of GaN Crystal Substrate The GaN crystal substrate was grown in the same manner as in Example A4 except that the grown GaN crystal was sliced along a plane parallel to the plane off by 0.4 ° in the [1-100] direction from the (0001) plane. A crystal substrate was obtained.

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 0.4 ° from the (0001) to the [1-100] direction, and the dislocation densities in the low dislocation density crystal region and the high dislocation density crystal region are respectively 1.60 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Here, the dislocation density was measured in the same manner as in Example A1. Further, since the number of dislocation concentration regions per 20 mm square is 14 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 14 pieces / area. Here, the number of dislocation concentration regions was measured by measuring the number of dark spot aggregate regions appearing in a low dislocation density region appearing as a bright portion in CL (cathode luminescence) observation. The carrier concentration was 5.11 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.39. The carrier concentration and C / F ratio were measured in the same manner as in Example A1.

In the GaN crystal substrate, the curvature radius in the [1-100] direction of the main surface is 18.5 m, and the off angle at the center of the main surface and the off angle at the end in the [1-100] direction from the center. The first deviation angle (hereinafter referred to as the first deviation angle in the [1-100] direction of the main surface), which is the difference between them, was 0.06 °. The radius of curvature of the main surface in the [11-20] direction is 9.7 m, which is the difference between the off angle at the center of the main surface and the off angle at the end in the [11-20] direction from the center. The second deviation angle (hereinafter referred to as the second deviation angle in the [11-20] direction of the main surface) was 0.12 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.06 °. Here, the first deviation angle and the second deviation angle were measured in the same manner as in Example A1. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.3 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 26.3 μm. Therefore, the size of one low dislocation density crystal region was 19933.4 μm × 1986.9 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
Referring to FIGS. 12 and 15, a GaN layer having a thickness of 5 μm is formed as at least one group III nitride semiconductor epitaxial layer 30 by MOCVD on main surface 20m of GaN crystal substrate 20p prepared as described above. A GaN crystal substrate with a semiconductor epitaxial layer was produced by growth. The growth conditions of the GaN layer (group III nitride semiconductor epitaxial layer 30) are a growth temperature of 1050 ° C., and a supply molar ratio of TMG (trimethylgallium) gas to NH ₃ gas ([V] / [III]) is 1250. It is desirable that it is 10,000. By using a high supply molar ratio, the amount of carbon occupying the group V site can be reduced. If the supply molar ratio ([V] / [III]) is too high, the crystal growth interface is covered with N, making it difficult for Ga to reach and increasing Ga missing defects.

In the obtained GaN layer (group III nitride semiconductor epitaxial layer 30), an epitaxial abnormal growth region 30ei having a width W _ei of 400 μm as shown in FIG. 13 was formed. A normal epitaxial growth region other than the epitaxial abnormal growth region 30ei of the GaN layer is a surface obtained by taking off the off-angle of the GaN crystal substrate 20p and turning off the GaN layer by 0.4 ° in the [1-100] direction from the (0001) plane. Although the crystal grows, the epitaxial abnormal growth region 30ei grows on the (0001) plane. The boundary between the epitaxially abnormal growth region 30ei and other regions is observed with a microscope. It can be confirmed by CV (capacitance-voltage) measurement that the epitaxial abnormal growth region 30ei has a lower carrier concentration in the epi layer than other regions. It can also be confirmed from the height distribution of the crystal growth surface observed using a laser microscope.

In the GaN layer (group III nitride semiconductor epitaxial layer 30), the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 1.60 × 10 ⁵ cm ⁻² and 8.50 × 10 respectively. ⁸ cm ^−2, which is equivalent to the dislocation densities of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p, respectively. The carrier concentration was 7.0 × 10 ¹⁵ m ⁻³ .

3. Fabrication of Semiconductor Device Referring to FIG. 15, a GaN crystal substrate with a semiconductor epitaxial layer obtained above (a GaN layer (group III nitride semiconductor epitaxial layer 30) was grown on main surface 20m of GaN crystal substrate 20p). The ohmic electrode 42 was formed on the other main surface 20n of the GaN crystal substrate 20p. Specifically, first, the main surface 20n of the GaN crystal substrate 20p was cleaned with organic cleaning and hydrochloric acid. Thereafter, layers of metal materials of 20 nm, 100 nm, 20 nm, and 200 nm, respectively, in the order of Ti, Al, Ti, and Au were formed on the entire main surface 20n by EB (electron beam) evaporation. Thereafter, heat treatment was performed at 600 ° C. for about 2 minutes in a nitrogen atmosphere, and the metal material layer was alloyed to form the ohmic electrode 42.

  Next, Ni—Au is formed on the main surface 30m of the GaN layer (group III nitride semiconductor epitaxial layer 30) in the region 40k immediately above and directly below the low dislocation density crystal region 20k of the GaN crystal substrate 20p. The Schottky electrode 41 having a diameter of 1600 μm and a thickness of 350 nm was formed by vapor deposition. Specifically, by photolithography, on the main surface 30m of the GaN layer (group III nitride semiconductor epitaxial layer 30), in the region 40k immediately above and immediately below the low dislocation density crystal region 20k of the GaN crystal substrate 20p. A resist having a circular opening located was formed (not shown). Thereafter, the surface treatment of the GaN layer (group III nitride semiconductor epitaxial layer 30) by hydrochloric acid cleaning was performed at room temperature for 3 minutes. Next, an N layer having a thickness of 50 nm was formed as the first metal layer to be the first layer 41a of the Schottky electrode 41 by EB vapor deposition. On the first metal layer, an Au layer having a thickness of 300 nm was formed as a second metal layer to be the second layer 41b by a resistance heating vapor deposition method. Thereafter, when the resist is removed, the metal layer formed on the resist is removed at the same time (lift-off), and a metal layer to be the Schottky electrode 41 is formed. Such a metal layer was formed so that its planar shape was circular.

  Next, the GaN crystal substrate 20p, the group III nitride semiconductor epitaxial layer 30, the Schottky electrode 41, and the ohmic electrode 42 constituting each SBD are all made of the wafer-like SBD into the low dislocation density crystal region 20k of the GaN crystal substrate 20p. The wafer-like SBD (wafer-like semiconductor device 40) is placed so as to be within the region 40k immediately above and below, and so that the main surface of the chipped SBD after division is substantially square and the area thereof is maximized. ) Was divided by the dividing line 40b to obtain an SBD (chip-formed semiconductor device 40c) chip-sized to a size of 19933.4 μm × 1986.9 μm.

The obtained chipped SBD (chiped semiconductor device 40c) has a C / F ratio of 0.39, a breakdown voltage yield of 0.50, and an average on-resistance of 0.90 mΩ · cm ² . Yes, the maximum on-resistance was 1.20 mΩ · cm ² , and the maximum operating current (referred to as the maximum current calculated to flow 500 A per 1 cm ² of electrode area during operation; the same shall apply hereinafter) was 10 A.

Here, with respect to the breakdown voltage yield, when the current density is 0.001 A · cm ⁻² , the SBD in which the reverse voltage reaches 600 V without leaking current is non-defective, and the current leaks without the reverse breakdown voltage reaching 600 V. The yield rate (the number of non-defective products) / (the number of non-defective products + the number of defective products) was calculated as a defective product. As for the average on-resistance and the maximum on-resistance, the change of the current that flows when voltage is applied to all SBDs obtained from one wafer-like SBD from 0 V to 3 V, respectively. Was measured with a parameter analyzer, and a change in voltage with respect to a change in current was calculated as an on-resistance, and an average value thereof was defined as an average on-resistance, and a maximum value thereof was defined as a maximum on-resistance. The maximum operating current was calculated assuming that 500 A per 1 cm ^{2 of} electrode area can be flowed, and the current of that magnitude was actually passed and confirmed. The results are summarized in Table 3. Note that the measurement of voltage, current, and resistance for calculating the breakdown voltage yield, average on-resistance, and maximum on-resistance of the chipped SBD was performed using a chip-shaped SBD that was dedicated for mounting in each of the examples and comparative examples. The package was mounted by die bonding the ohmic electrode 42 side of the SBD and wire bonding the Schottky electrode 41 side of the SBD.

(Example B2)
1. Preparation of GaN crystal substrate The pitches P _M1 and P _M2 of the first and second stripe masks formed on the main surface of the GaAs substrate (underlying substrate) during the growth of the GaN crystal were set to 800 μm and grown. A GaN crystal substrate was obtained in the same manner as in Example B1, except that the GaN crystal was sliced along a plane parallel to the main surface ((111) A plane) of the GaAs substrate (underlying substrate).

The obtained GaN crystal substrate has a plane orientation of (0001) on the principal surface, and the dislocation densities of the low dislocation density crystal region and the high dislocation density crystal region are 2.00 × 10 ⁴ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 8 and the number of low dislocation density crystal regions per 20 mm square is 625, the density of dislocation concentration regions per one dislocation density crystal region is 0. 01 / area. The carrier concentration was 5.40 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.70. Further, the radius of curvature in the [1-100] direction of the main surface was 28.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.04 °. The radius of curvature in the [11-20] direction of the main surface was 15.6 m, and the second deviation angle in the [11-20] direction of the main surface was 0.07 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.03 °. Further, the first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 800 μm and a width W ₁ of 13.4 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 800 μm and a width W ₂ of 26.4 μm. For this reason, the size of one low dislocation density crystal region was 793.3 μm × 786.8 μm. 2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 2.00 × 10 ⁴ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Fabrication of Semiconductor Device SBD (chip-formed semiconductor device 40c) formed into a chip size of 793.3 μm × 786.8 μm in the same manner as in Example B1 except that the diameter of the Schottky electrode 41 is set to 600 μm. ) The obtained chipped SBD has a C / F ratio of 0.70, a breakdown voltage yield of 0.92, an average on-resistance of 1.10 mΩ · cm ² , and a maximum on-resistance of 1.39 mΩ. • cm ² and the maximum operating current was 1.5A. The results are summarized in Table 3.

(Example B3)
1. Preparation of GaN Crystal Substrate Example, except that the pitches P _M1 and P _M2 of the first and second stripe masks formed on the main surface of the GaAs substrate (underlying substrate) during the growth of the GaN crystal were set to 1500 μm, respectively. A GaN crystal substrate was obtained in the same manner as B2.

The obtained GaN crystal substrate has a plane orientation of (0001) on the principal surface, and the dislocation densities in the low dislocation density crystal region and the high dislocation density crystal region are 6.75 × 10 ⁴ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 12 and the number of low dislocation density crystal regions per 20 mm square is 178, the density of dislocation concentration regions per one dislocation density crystal region is 0. It was 07 pieces / area. The carrier concentration was 5.55 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.41. Moreover, the curvature radius in the [1-100] direction of the main surface was 20.1 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 10.8 m, and the second deviation angle in the [11-20] direction of the main surface was 0.11 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.05 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 1500 μm and a width W ₁ of 13.3 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 1500 μm and a width W ₂ of 26.5 μm. Therefore, the size of one low dislocation density crystal region was 1493.4 μm × 1486.8 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 6.75 × 10 ⁴ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Fabrication of Semiconductor Device SBD (chip-formed semiconductor device 40c) chip-sized to 1493.4 μm × 1486.8 μm in the same manner as in Example B1 except that the diameter of the Schottky electrode 41 is 1200 μm. ) The obtained chipped SBD has a C / F ratio of 0.41, a breakdown voltage yield of 0.88, an average on-resistance of 0.96 mΩ · cm ² , and a maximum on-resistance of 1.38 mΩ. • cm ² and the maximum operating current was 6A. The results are summarized in Table 3.

(Example B4)
1. Preparation of GaN crystal substrate A GaN crystal substrate was obtained in the same manner as in Example B1, except that the grown GaN crystal was sliced along a plane parallel to the (0001) plane. The preparation method of the GaN crystal substrate in Example B4 is that the pitches P _M1 and P _M2 of the first and second stripe masks formed on the main surface of the GaAs substrate (underlying substrate) during the growth of the GaN crystal are set. Example B2 is the same as Example B2 except that the thickness is 2000 μm.

The obtained GaN crystal substrate has a plane orientation of (0001) on the principal surface, and the dislocation densities of the low dislocation density crystal region and the high dislocation density crystal region are 1.60 × 10 ⁵ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 14 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 14 pieces / area. The carrier concentration was 5.11 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.39. Further, the radius of curvature in the [1-100] direction of the main surface was 18.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 9.7 m, and the second deviation angle in the [11-20] direction of the main surface was 0.12 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.06 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.0 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 26.0 μm. Therefore, the size of one low dislocation density crystal region was 1993.5 μm × 1987.0 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 1.60 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode 41 diameter of 1600 μm and chipped to a size of 1993.5 μm × 1987.0 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.39, a breakdown voltage yield of 0.80, an average on-resistance of 0.98 mΩ · cm ² , and a maximum on-resistance of 1.39 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 3.

(Comparative Example RB1)
1. Preparation of GaN Crystal Substrate A GaN crystal substrate similar to Comparative Example RA1 was prepared.

The prepared GaN crystal substrate has a principal surface with a plane orientation of (0001), and the dislocation density in the low dislocation density crystal region and the high dislocation density crystal region is 3.15 × 10 ⁴ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 50 and the number of low dislocation density crystal regions per 20 mm square is 50, the density of dislocation concentration regions per one dislocation density crystal region is 1. It was 00 / area. However, in this comparative example, since the low dislocation density crystal region has a stripe shape, a plurality of square semiconductor devices are taken from one low dislocation density crystal region. In the embodiment, one semiconductor device is taken from one low dislocation density crystal region. From this point of view, one low dislocation density crystal region in this comparative example corresponds to 50 low dislocation density crystal regions in the examples. That is, since the number of low dislocation density crystal regions corresponding to the examples per 20 mm square is 2500, the density of dislocation concentrated regions per one example equivalent dislocation density crystal region was 0.02 / region. .

The carrier concentration was 4.28 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.80. Further, the radius of curvature in the [1-100] direction of the main surface was 32.4 m, and the first deviation angle in the [1-100] direction of the main surface was 0.04 °. Further, the radius of curvature in the [11-20] direction of the main surface was 6.8 m, and the second deviation angle in the [11-20] direction of the main surface was 0.16 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.12 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 400 μm and a width W ₁ of 13.1 μm. For this reason, the size of one low dislocation density crystal region in a 20 mm square was 395.5 μm × 20000 μm (20 mm).

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 3.15 × 10 ⁴ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Fabrication of Semiconductor Device A wafer-like SBD (wafer-like semiconductor device 40) is formed by forming an ohmic electrode 42 and a Schottky electrode 41 in the same manner as in Example B1 except that the diameter of the Schottky electrode 41 is 200 μm. Got. Next, the wafer-like SBD is formed immediately above and immediately below the low dislocation density crystal region of the GaN crystal substrate, with the GaN crystal substrate, the group III nitride semiconductor epitaxial layer, the Schottky electrode, and the ohmic electrode constituting each SBD. The wafer-like SBD (wafer-like semiconductor device) is divided so as to fit within the region (not shown) and so that the main surface of the chipped SBD after division is almost square and its area is maximized. Thus, an SBD (chip semiconductor device 40c) chipped to a size of 395.5 μm × 400.0 μm was obtained.

The obtained chipped SBD has a C / F ratio of 0.80, a breakdown voltage yield of 0.95, an average on-resistance of 1.38 mΩ · cm ² , and a maximum on-resistance of 2.34 mΩ. -Cm ² and the maximum operating current was 0.15A. The results are summarized in Table 3.

(Comparative Example RB2)
1. Preparation of GaN Crystal Substrate Similar to Comparative Example RB1, except that the pitch P _M1 of the first stripe mask formed on the main surface of the GaAs substrate (underlying substrate) during the growth of the GaN crystal was 2000 μm, GaN A crystal substrate was obtained.

The obtained GaN crystal substrate has a plane orientation of (0001) on the principal surface, and the dislocation densities in the low dislocation density crystal region and the high dislocation density crystal region are 8.00 × 10 ⁶ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 700 and the number of low dislocation density crystal regions per 20 mm square is 10, the density of dislocation concentration regions per one dislocation density crystal region is 70. 0 / area. Here, from the same viewpoint as the comparative example RB1, one low dislocation density crystal region of this comparative example corresponds to ten low dislocation density crystal regions in the examples. That is, since the number of low dislocation density crystal regions corresponding to the example per 20 mm square is 100, the density of dislocation concentration regions per one example equivalent dislocation density crystal region was 7.00 / region. .

The carrier concentration was 5.18 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.55. Further, the radius of curvature in the [1-100] direction of the main surface was 18.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 5.7 m, and the second deviation angle in the [11-20] direction of the main surface was 0.20 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.14 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.5 μm. For this reason, the size of one low dislocation density crystal region in a 20 mm square was 19933.3 μm × 20000 μm (20 mm).

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 8.00 × 10 ⁶ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Fabrication of Semiconductor Device SBD (chip semiconductor device 40c) chipped to a size of 19933.3 μm × 2000.0 μm in the same manner as Comparative Example RB1, except that the diameter of the Schottky electrode was 1600 μm Got. The obtained chipped SBD has a C / F ratio of 0.55, a breakdown voltage yield of 0.02, an average on-resistance of 1.09 mΩ · cm ² , and a maximum on-resistance of 2.28 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 3.

(Comparative Example RB3)
1. Preparation of GaN Crystal Substrate Similar to Comparative Example RB1, except that the pitch P _M1 of the first stripe mask formed on the main surface of the GaAs substrate (underlying substrate) during the growth of the GaN crystal was set to 5000 μm. A crystal substrate was obtained.

The obtained GaN crystal substrate has a plane orientation of (0001) on the principal surface, and the dislocation densities of the low dislocation density crystal region and the high dislocation density crystal region are 2.05 × 10 ⁷ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 2200 and the number of low dislocation density crystal regions per 20 mm square is 4, the density of dislocation concentration regions per one dislocation density crystal region is 550. 0 / area. Here, from the same viewpoint as the comparative example RB1, one low dislocation density crystal region of this comparative example corresponds to four low dislocation density crystal regions in the examples. That is, since the number of low dislocation density crystal regions corresponding to the examples per 20 mm square is 16, the density of dislocation concentrated regions per one example equivalent dislocation density crystal region was 137.5 / region. .

The carrier concentration was 5.20 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.36. Further, the radius of curvature in the [1-100] direction of the main surface was 9.2 m, and the first deviation angle in the [1-100] direction of the main surface was 0.12 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 2.4 m, and the second deviation angle in the [11-20] direction of the main surface was 0.48 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.36 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 5000 μm and a width W ₁ of 13.8 μm. For this reason, the size of one low dislocation density crystal region in a 20 mm square was 4993.1 μm × 20000 μm (20 mm).

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 2.05 × 10 ⁷ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Fabrication of Semiconductor Device SBD chipped into a size of 4993.1 μm × 5000.0 μm in the same manner as Comparative Example RB1 except that the diameter of the Schottky electrode was 4500 μm (chiped semiconductor device 40c) Got. The obtained chipped SBD had a C / F ratio of 0.36 and a withstand voltage yield of 0.00. That is, good SBD was not obtained. The results are summarized in Table 3.

(Example B5)
1. Preparation of GaN Crystal Substrate Example, except that the pitches P _M1 and P _M2 of the first and second stripe masks formed on the main surface of the GaAs substrate (underlying substrate) during the growth of the GaN crystal were 9500 μm, respectively. A GaN crystal substrate was obtained in the same manner as B2.

The obtained GaN crystal substrate has a plane orientation of (0001) on the principal surface, and the dislocation densities of the low dislocation density crystal region and the high dislocation density crystal region are 8.30 × 10 ⁵ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 20 and the number of low dislocation density crystal regions per 20 mm square is 4.2, the density of dislocation concentration regions per one dislocation density crystal region is 4.76 pieces / area. The carrier concentration was 5.00 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.20. Further, the radius of curvature in the [1-100] direction of the main surface was 13.0 m, and the first deviation angle in the [1-100] direction of the main surface was 0.09 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 9.5 m, and the second deviation angle in the [11-20] direction of the main surface was 0.12 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.03 °. Further, the first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 9500 μm and a width W ₁ of 13.2 μm. Further, the second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 9500 μm and a width W ₂ of 26.5 μm. Therefore, the size of one low dislocation density crystal region was 9493.4 μm × 9486.8 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 8.30 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Fabrication of Semiconductor Device SBD chipped into a size of 9493.4 μm × 9486.8 μm in the same manner as in Example B1 except that the diameter of the Schottky electrode was set to 9000 μm (chiped semiconductor device 40c) Got. The obtained chipped SBD has a C / F ratio of 0.20, a breakdown voltage yield of 0.45, an average on-resistance of 0.86 mΩ · cm ² , and a maximum on-resistance of 1.37 mΩ. • cm ² and the maximum operating current was 300A. The results are summarized in Table 4.

(Example B6)
1. Preparation of GaN Crystal Substrate Embodiments except that the pitches P _M1 and P _M2 of the first and second stripe masks formed on the main surface of the GaAs substrate (underlying substrate) during the growth of the GaN crystal were set to 10,000 μm, respectively. A GaN crystal substrate was obtained in the same manner as B2.

The obtained GaN crystal substrate has a principal plane with a plane orientation of (0001), and the dislocation densities in the low dislocation density crystal region and the high dislocation density crystal region are 8.80 × 10 ⁵ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 22 and the number of low dislocation density crystal regions per 20 mm square is 4, the density of dislocation concentration regions per one dislocation density crystal region is 5. 50 / area. The carrier concentration was 5.25 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.18. Further, the radius of curvature in the [1-100] direction of the main surface was 11.6 m, and the first deviation angle in the [1-100] direction of the main surface was 0.10 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 9.0 m, and the second deviation angle in the [11-20] direction of the main surface was 0.13 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.03 °. The first stripe crystal region of high dislocation density regions in the main surface, the pitch P ₁ is at 10000, the width W ₁ was 13.0. The second stripe crystal region of high dislocation density crystal region in the main surface, the pitch P ₂ is at 10000, the width W ₂ was 26.3Myuemu. Therefore, the size of one low dislocation density crystal region was 9993.5 μm × 9986.9 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 8.80 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Fabrication of Semiconductor Device SBD chipped to a size of 9993.5 μm × 9986.9 μm (Semiconductor device 40c chipped) in the same manner as Example B1 except that the diameter of the Schottky electrode was 9500 μm Got. The obtained chipped SBD has a C / F ratio of 0.18, a breakdown voltage yield of 0.40, an average on-resistance of 0.83 mΩ · cm ² , and a maximum on-resistance of 1.40 mΩ. • cm ² and maximum operating current was 350A. The results are summarized in Table 4.

(Example B7)
1. Preparation of GaN crystal substrate Except that the partial pressure of O ₂ gas for doping O (oxygen) into the crystal during the growth of the GaN crystal by the HVPE method was set to 6 × 10 ⁻⁷ atm (0.06 Pa), A GaN crystal substrate was obtained in the same manner as Example B4.

The obtained GaN crystal substrate has a plane orientation of (0001) on the principal surface, and the dislocation densities of the low dislocation density crystal region and the high dislocation density crystal region are 1.80 × 10 ⁵ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 13 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 13 / area. The carrier concentration was 8.21 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.38. Further, the radius of curvature in the [1-100] direction of the main surface was 18.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 10.8 m, and the second deviation angle in the [11-20] direction of the main surface was 0.11 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.05 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.3 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 26.4 μm. Therefore, the size of one low dislocation density crystal region was 19933.4 μm × 1986.8 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 1.80 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 19933.4 μm × 1986.8 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.38, a breakdown voltage yield of 0.78, an average on-resistance of 0.82 mΩ · cm ² , and a maximum on-resistance of 1.19 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 4.

(Example B8)
1. Preparation of GaN crystal substrate Except that the partial pressure of O ₂ gas for doping O (oxygen) into the crystal during the growth of GaN crystal by the HVPE method is 1.2 × 10 ⁻⁶ atm (0.12 Pa) Obtained a GaN crystal substrate in the same manner as in Example B4.

The obtained GaN crystal substrate has a plane orientation of (0001) on the principal surface, and the dislocation densities of the low dislocation density crystal region and the high dislocation density crystal region are 1.70 × 10 ⁵ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 13 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 13 / area. The carrier concentration was 1.20 × 10 ¹⁹ cm ⁻³ and the C / F ratio was 0.35. Further, the radius of curvature in the [1-100] direction of the main surface was 18.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 10.8 m, and the second deviation angle in the [11-20] direction of the main surface was 0.11 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.05 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.4 μm. Further, the second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 26.2 μm. Therefore, the size of one low dislocation density crystal region was 19933.3 μm × 1986.9 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 1.70 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 1993.3.3 μm × 1986.9 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.35, a breakdown voltage yield of 0.77, an average on-resistance of 0.72 mΩ · cm ² , and a maximum on-resistance of 1.05 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 4.

(Example B9)
1. Preparation of GaN Crystal Substrate In the same manner as in Example B4, except that the grown GaN crystal was sliced along a plane parallel to a plane off by 0.7 ° in the [1-100] direction from the (0001) plane, A crystal substrate was obtained.

In the obtained GaN crystal substrate, the plane orientation of the principal surface is 0.7 ° off from the (0001) to the [1-100] direction, and the dislocation densities in the low dislocation density crystal region and the high dislocation density crystal region are respectively 1.60 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 14 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 14 pieces / area. The carrier concentration was 5.11 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.39. Further, the radius of curvature in the [1-100] direction of the main surface was 18.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 9.7 m, and the second deviation angle in the [11-20] direction of the main surface was 0.12 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.06 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.1 μm. Further, the second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 26.5 μm. Therefore, the size of one low dislocation density crystal region was 1993.5 μm × 1986.8 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), an epitaxial abnormal growth region 30ei having a width W _ei of 200 μm as shown in FIG. 13 was formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 1.60 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and having a size of 1993.5 μm × 1986.8 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.39, a breakdown voltage yield of 0.80, an average on-resistance of 0.90 mΩ · cm ² , and a maximum on-resistance of 1.20 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 4.

  The following was found with reference to Tables 3 and 4 above. An SBD including a GaN crystal substrate having a stripe-shaped high dislocation density crystal region has a high C / F ratio, so that both the average on-resistance and the maximum on-resistance are high. As the interval between the high dislocation density crystal regions increases, the breakdown voltage yield increases. It was greatly reduced (Comparative Examples RB1, RB2, RB3). In contrast, an SBD including a GaN crystal substrate having a lattice-like high dislocation density crystal region has a low C / F ratio, so that both the average on-resistance and the maximum on-resistance are low, and the interval between the high dislocation density crystal regions is small. Even if it became large, the pressure | voltage resistant yield was maintained high (Example B1-B9). This is presumably because the C / F ratio was lowered and the formation of dislocation concentrated regions was suppressed at a low dislocation density by forming the high dislocation density of the GaN crystal substrate in a lattice shape. Moreover, it is thought that the average on-resistance and the maximum on-resistance of the SBD including the GaN crystal substrate having a high carrier concentration are low because the resistance of the GaN crystal substrate is reduced (Examples B4, B7, and B8). That is, it is considered that the average on-resistance and the maximum on-resistance can be lowered by lowering the C / F ratio and / or increasing the carrier concentration of the GaN crystal substrate. Further, it is considered that the reduction of the dislocation density and the dislocation concentration region of the GaN crystal substrate greatly contributes to the improvement of the breakdown voltage yield of the SBD including the GaN crystal substrate having a high carrier concentration.

(Example B10)
1. Preparation of GaN Crystal Substrate Example B1 except that the first stripe mask formed on the main surface of the GaAs substrate (underlying substrate) during the growth of the GaN crystal is continuous and the second stripe mask is discontinuous. Similarly, a GaN crystal substrate was obtained. The second stripe mask discontinuities repeated continuous portion at constant intervals, the length L _MW discontinuities is 2 [mu] m, the length L _M of the continuous portion was 40 [mu] m.

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 0.4 ° from the (0001) to the [1-100] direction, and the dislocation densities in the low dislocation density crystal region and the high dislocation density crystal region are respectively They were 2.00 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 13 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 13 / area. The carrier concentration was 6.01 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.30. Further, the radius of curvature in the [1-100] direction of the main surface was 18.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 9.5 m, and the second deviation angle in the [11-20] direction of the main surface was 0.11 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.05 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.4 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 24.5 μm. In the second stripe crystal region, the discontinuous portion and the continuous portion were repeated at regular intervals, the length L _W of the discontinuous portion was 17.5 μm, and the length L of the continuous portion was 24.5 μm. For this reason, the size of one low dislocation density crystal region was 19933.3 μm × 1987.8 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei as in Example B1 was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 2.00 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 193.3 μm × 19878 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.30, a breakdown voltage yield of 0.85, an average on-resistance of 0.86 mΩ · cm ² , and a maximum on-resistance of 1.25 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 5.

(Example B11)
1. Prepare second stripe mask GaN crystal substrate, repeated at discontinuous portions and continuous portions is constant intervals, 100 [mu] m length L _MW of discontinuities, except that the length L _M of the continuous portion is set to 40 [mu] m, performed A GaN crystal substrate was obtained in the same manner as in Example B12. .

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 0.4 ° from the (0001) to the [1-100] direction, and the dislocation densities in the low dislocation density crystal region and the high dislocation density crystal region are respectively They were 5.00 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 18 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 18 / area. The carrier concentration was 6.01 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.30. Further, the radius of curvature in the [1-100] direction of the main surface was 18.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 9.5 m, and the second deviation angle in the [11-20] direction of the main surface was 0.11 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.05 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.2 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 24.0 μm. In the second stripe crystal region, the discontinuous portion and the continuous portion were repeated at regular intervals, the length L _W of the discontinuous portion was 116 μm, and the length L of the continuous portion was 24.0 μm. For this reason, the size of one low dislocation density crystal region was 1993.4 μm × 1988.0 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei as in Example B1 was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 5.00 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 19933.4 μm × 1988.0 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.30, a breakdown voltage yield of 0.77, an average on-resistance of 0.86 mΩ · cm ² , and a maximum on-resistance of 1.25 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 5.

(Example B12)
1. Preparation of GaN Crystal Substrate Example B4 except that a GaAs substrate having a principal plane orientation of 10 ° off from (111) A in the [1-10] direction was used as the base substrate during the growth of the GaN crystal. In the same manner as above, a GaN crystal substrate was obtained.

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 10 ° from the (0001) direction to the [11-20] direction, and the dislocation density in the low dislocation density crystal region and the high dislocation density crystal region is 1. They were 88 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 14 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 14 pieces / area. The carrier concentration was 6.50 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.50. Further, the radius of curvature in the [1-100] direction of the main surface was 36.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.03 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 4.50 m, and the second deviation angle in the [11-20] direction of the main surface was 0.25 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.22 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.5 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 24.3 μm. Therefore, the size of one low dislocation density crystal region was 19933.3 μm × 1987.9 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 1.88 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped into a size of 193.3 μm × 1987.9 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.50, a breakdown voltage yield of 0.78, an average on-resistance of 0.96 mΩ · cm ² , and a maximum on-resistance of 1.36 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 5.

(Example B13)
1. Preparation of GaN Crystal Substrate Example B4 except that a GaAs substrate having a main surface orientation of 25 ° off from the (111) A in the [1-10] direction was used as the base substrate during the growth of the GaN crystal. In the same manner as above, a GaN crystal substrate was obtained.

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 25 ° from the (0001) direction to the [11-20] direction, and the dislocation density in the low dislocation density crystal region and the high dislocation density crystal region is 2. 10 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 18 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 18 / area. The carrier concentration was 6.23 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.23. Further, the radius of curvature in the [1-100] direction of the main surface was 17.6 m, and the first deviation angle in the [1-100] direction of the main surface was 0.07 °. Further, the radius of curvature in the [11-20] direction of the main surface was 3.12 m, and the second deviation angle in the [11-20] direction of the main surface was 0.37 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.30 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 9.5 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 23.2 μm. Therefore, the size of one low dislocation density crystal region was 19955.3 μm × 1988.4 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 2.10 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 195.3 μm × 1988.4 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.23, a breakdown voltage yield of 0.61, an average on-resistance of 0.80 mΩ · cm ² , and a maximum on-resistance of 1.40 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 5.

(Example B14)
1. Preparation of GaN Crystal Substrate Example B4 except that a GaAs substrate having a principal plane orientation of 10 ° off from the (111) A in the [11-2] direction was used as the base substrate during the growth of the GaN crystal. In the same manner as above, a GaN crystal substrate was obtained.

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 10 ° from the (0001) to the [1-100] direction, and the dislocation density in the low dislocation density crystal region and the high dislocation density crystal region is 1. They were 98 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 13 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 13 / area. The carrier concentration was 6.30 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.48. Further, the radius of curvature in the [1-100] direction of the main surface was 4.40 m, and the first deviation angle in the [1-100] direction of the main surface was 0.26 °. Further, the radius of curvature in the [11-20] direction of the main surface was 22.1 m, and the second deviation angle in the [11-20] direction of the main surface was 0.05 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.21 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 12.5 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 24.5 μm. Therefore, the size of one low dislocation density crystal region was 1993.8 μm × 1987.8 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 1.98 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 1993.8 μm × 19878 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.48, a breakdown voltage yield of 0.82, an average on-resistance of 0.96 mΩ · cm ² , and a maximum on-resistance of 1.38 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 5.

(Example B15)
1. Preparation of GaN Crystal Substrate Example B4 except that a GaAs substrate having a main surface orientation of 25 ° off from the (111) A to the [11-2] direction was used as the base substrate during the growth of the GaN crystal. In the same manner as above, a GaN crystal substrate was obtained.

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 25 ° from the (0001) to the [1-100] direction, and the dislocation density in the low dislocation density crystal region and the high dislocation density crystal region is 2. They were 30 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 19 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per dislocation density crystal region is 0. 19 / area. The carrier concentration was 6.03 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.20. Moreover, the curvature radius in the [1-100] direction of the main surface was 2.95 m, and the first deviation angle in the [1-100] direction of the main surface was 0.40 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 11.0 m, and the second deviation angle in the [11-20] direction of the main surface was 0.10 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.30 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 10.3 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 22.5 μm. Therefore, the size of one low dislocation density crystal region was 19944.9 μm × 1988.8 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 2.30 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 19944.9 μm × 1988.8 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.20, a breakdown voltage yield of 0.63, an average on-resistance of 0.79 mΩ · cm ² , and a maximum on-resistance of 1.42 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 5.

  As is clear when referring to Examples B1 and B4 in Table 3, Example B9 in Table 4, and Examples B10 to B15 in Table 5, the main surface is slightly off-angle (e.g., 0.4 from the (0001) plane). In the group III nitride semiconductor epitaxial layer grown on the main surface of the GaN crystal substrate (Examples B1 and B9) having a ° or 0.7 degree), an epitaxial abnormal growth region was formed. The off-angle of the main surface of the GaN crystal substrate (Examples B10 and B11) or the GaN crystal substrate in which one of the first and second stripe crystal regions of the region is discontinuous is 0 °, 10 ° from the (0001) plane Alternatively, no abnormal epitaxial growth region was formed in the group III nitride semiconductor epitaxial layer grown on the main surface of the GaN crystal substrate (Examples B4, B12 to B15) at 25 °.

  Examples B16 to B21 and B24 below are examples in which a GaN crystal substrate is manufactured using a GaAs substrate (underlying substrate) having a diameter of 4 inches (10.16 cm). In these embodiments, the first deviation angle in the [1-100] direction of the main surface and the second deviation angle in the [11-20] direction of the main surface are respectively an off angle and a center point at the center point of the main surface. The difference between the off-angle at the end point 4 cm away from the center and the off-angle at the center point of the main surface and the end point 4 cm away from the center point in the [11-20] direction It was calculated from the difference between the off-angle at. Here, the off angle of the principal surface at each point is calculated from the plane orientation of the point measured by the ω-rocking curve with respect to the (0002) plane by X-ray diffraction at that point.

(Example B16)
1. Preparation of GaN Crystal Substrate During the growth of GaN crystal, the first stripe mask formed on the main surface of a GaAs substrate (underlying substrate) having a diameter of 4 inches (10.16 cm) is continuous, and the second stripe mask is not used. A GaN crystal substrate was obtained in the same manner as in Example B4, except that it was continuous. The second stripe mask discontinuities repeated continuous portion at constant intervals, the length L _MW discontinuities is 2 [mu] m, the length L _M of the continuous portion was 40 [mu] m.

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 0.4 ° from the (0001) to the [1-100] direction, and the dislocation densities in the low dislocation density crystal region and the high dislocation density crystal region are respectively 1.90 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 15 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 15 / area. The carrier concentration was 6.23 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.29. Further, the radius of curvature in the [1-100] direction of the main surface was 37.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 25.3 m, and the second deviation angle in the [11-20] direction of the main surface was 0.10 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.04 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.4 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 24.5 μm. In the second stripe crystal region, the discontinuous portion and the continuous portion were repeated at regular intervals, the length L _W of the discontinuous portion was 17.5 μm, and the length L of the continuous portion was 24.5 μm. For this reason, the size of one low dislocation density crystal region was 19933.3 μm × 1987.8 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
Similar to Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei as in Example B1 was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 1.90 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 193.3 μm × 19878 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.29, a breakdown voltage yield of 0.84, an average on-resistance of 0.81 mΩ · cm ² , and a maximum on-resistance of 1.30 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 6.

(Example B17)
Prepare second stripe mask GaN crystal substrate, repeated at discontinuous portions and continuous portions is constant intervals, 100 [mu] m length L _MW of discontinuities, except that the length L _M of the continuous portion is set to 40 [mu] m, performed A GaN crystal substrate was obtained in the same manner as in Example B16. .

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 0.4 ° from the (0001) to the [1-100] direction, and the dislocation densities in the low dislocation density crystal region and the high dislocation density crystal region are respectively It was 4.50 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 20 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 20 / area. The carrier concentration was 6.30 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.28. Further, the radius of curvature in the [1-100] direction of the main surface was 18.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.12 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 9.5 m, and the second deviation angle in the [11-20] direction of the main surface was 0.22 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.10 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.5 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 24.0 μm. In the second stripe crystal region, the discontinuous portion and the continuous portion were repeated at regular intervals, the length L _W of the discontinuous portion was 116 μm, and the length L of the continuous portion was 24.0 μm. Therefore, the size of one low dislocation density crystal region was 19933.3 μm × 1988.0 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
Similar to Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei as in Example B1 was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 4.50 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped into a size of 193.3 μm × 1988.0 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.28, a breakdown voltage yield of 0.72, an average on-resistance of 0.88 mΩ · cm ² , and a maximum on-resistance of 1.30 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 6.

(Example B18)
1. Preparation of GaN Crystal Substrate During growth of a GaN crystal, a GaAs substrate having a diameter of 4 inches (10.16 cm) as a base substrate and a plane orientation of the main surface off by (10) from (111) A to [1-10] direction A GaN crystal substrate was obtained in the same manner as Example B4 except that was used.

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 10 ° from the (0001) to the [11-20] direction, and the dislocation density in the low dislocation density crystal region and the high dislocation density crystal region is 2. They were 00 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 16 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per dislocation density crystal region is 0. 16 / area. The carrier concentration was 6.03 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.48. Further, the radius of curvature in the [1-100] direction of the main surface was 36.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 3.72 m, and the second deviation angle in the [11-20] direction of the main surface was 0.31 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.25 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.8 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 24.4 μm. For this reason, the size of one low dislocation density crystal region was 1993.1 μm × 1987.8 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 2.00 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 1993.1 μm × 1987.8 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.48, a breakdown voltage yield of 0.76, an average on-resistance of 1.00 mΩ · cm ² , and a maximum on-resistance of 1.33 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 5.

(Example B19)
1. Preparation of GaN crystal substrate GaAs substrate with a diameter of 4 inches (10.16 cm) and a principal plane orientation of 25 ° off from (111) A to [1-10] direction during the growth of GaN crystal A GaN crystal substrate was obtained in the same manner as Example B4 except that was used.

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 25 ° from the (0001) direction to the [11-20] direction, and the dislocation density in the low dislocation density crystal region and the high dislocation density crystal region is 2. They were 30 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 20 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 20 / area. Further, a carrier concentration of ^{6.80 × 10 18 cm -3, C} / F ratio was 0.35. Further, the radius of curvature in the [1-100] direction of the main surface was 35.6 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 3.10 m, and the second deviation angle in the [11-20] direction of the main surface was 0.36 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.30 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.3 μm. Further, the second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 23.8 μm. Therefore, the size of one low dislocation density crystal region was 1993.4 μm × 1988.1 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 2.30 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 19933.4 μm × 1988.1 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.35, a breakdown voltage yield of 0.60, an average on-resistance of 0.91 mΩ · cm ² , and a maximum on-resistance of 1.42 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 6.

(Example B20)
1. Preparation of GaN Crystal Substrate During growth of GaN crystal, a GaAs substrate with a diameter of 4 inches (10.16 cm) as a base substrate and a plane orientation of the main surface off (111) A by 10 ° in the [11-2] direction. A GaN crystal substrate was obtained in the same manner as Example B4 except that was used.

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 10 ° from the (0001) direction to the [1-100] direction, and the dislocation density in the low dislocation density crystal region and the high dislocation density crystal region is 2. They were 00 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 15 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 15 / area. The carrier concentration was 6.40 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.42. Moreover, the curvature radius in the [1-100] direction of the main surface was 3.85 m, and the first deviation angle in the [1-100] direction of the main surface was 0.29 °. Further, the radius of curvature in the [11-20] direction of the main surface was 19.5 m, and the second deviation angle in the [11-20] direction of the main surface was 0.12 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.17 °. Further, the first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 12.9 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 24.9 μm. Therefore, the size of one low dislocation density crystal region was 19933.6 μm × 1987.6 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 2.00 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 19933.6 μm × 1987.6 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.42, a breakdown voltage yield of 0.80, an average on-resistance of 0.95 mΩ · cm ² , and a maximum on-resistance of 1.34 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 6.

(Example B21)
1. Preparation of GaN Crystal Substrate During growth of a GaN crystal, a GaAs substrate having a diameter of 4 inches (10.16 cm) as a base substrate and a plane orientation of the principal surface off from (111) A to [11-2] direction by 25 ° A GaN crystal substrate was obtained in the same manner as Example B4 except that was used.

In the obtained GaN crystal substrate, the plane orientation of the main surface is off by 25 ° from the (0001) to the [1-100] direction, and the dislocation density in the low dislocation density crystal region and the high dislocation density crystal region is 2. They were 80 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 21 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 21 / area. The carrier concentration was 6.00 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.29. Further, the radius of curvature in the [1-100] direction of the main surface was 2.91 m, and the first deviation angle in the [1-100] direction of the main surface was 0.39 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 29.1 m, and the second deviation angle in the [11-20] direction of the main surface was 0.31 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.02 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.1 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 23.0 μm. Therefore, the size of one low dislocation density crystal region was 1993.5 μm × 1988.5 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example B1, a GaN crystal with a semiconductor epitaxial layer in which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above. A substrate was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 2.80 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 7.0 × 10 ¹⁵ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 1993.5 μm × 1988.5 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.29, a breakdown voltage yield of 0.69, an average on-resistance of 0.80 mΩ · cm ² , and a maximum on-resistance of 1.41 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 6.

  As is clear from reference to Examples B16 to B21 in Table 6 and Example B24 in Table 7 to be described later, even when the diameter of the GaN crystal substrate is as large as 4 inches, the main surface slightly differs from the (0001) plane. GaN crystal substrate in which either of the first and second stripe crystal regions of the high dislocation density crystal region is discontinuous even if it has an off angle (eg, 0.4 °) (Examples B16 and B17) Or a group III nitride grown on the main surface of a GaN crystal substrate (Examples B24, B18 to B21) in which the off-angle of the main surface of the GaN crystal substrate is 0 °, 10 ° or 25 ° from the (0001) plane No epitaxial abnormal growth region was formed in the semiconductor epitaxial layer.

(Example B22)
1. Preparation of GaN crystal substrate A GaN crystal substrate was obtained in the same manner as in Example B4.

The obtained GaN crystal substrate has a plane orientation of (0001) on the principal surface, and the dislocation densities of the low dislocation density crystal region and the high dislocation density crystal region are 1.70 × 10 ⁵ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 13 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 13 / area. The carrier concentration was 5.90 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.43. Further, the radius of curvature in the [1-100] direction of the main surface was 18.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 9.5 m, and the second deviation angle in the [11-20] direction of the main surface was 0.11 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.05 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.1 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 23.0 μm. Therefore, the size of one low dislocation density crystal region was 1993.5 μm × 1988.5 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In order to reduce the carrier concentration of the epitaxial layer, except that the inside of the chamber is made of a material not containing quartz, in the same manner as in Example B1, on the main surface 20m of the GaN crystal substrate 20p prepared as described above, A GaN crystal substrate with a semiconductor epitaxial layer on which a GaN layer (Group III nitride semiconductor epitaxial layer 30) having a thickness of 5 μm was formed was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 1.70 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 5.00 × 10 ¹⁴ cm ^-3.

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 1993.5 μm × 1988.5 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.43, a breakdown voltage yield of 0.81, an average on-resistance of 0.99 mΩ · cm ² , and a maximum on-resistance of 1.54 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 7.

(Example B23)
1. Preparation of GaN crystal substrate A GaN crystal substrate was obtained in the same manner as in Example B4.

The obtained GaN crystal substrate has a plane orientation of (0001) on the principal surface, and the dislocation densities of the low dislocation density crystal region and the high dislocation density crystal region are 1.80 × 10 ⁵ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ⁻² . Further, since the number of dislocation concentration regions per 20 mm square is 14 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 14 pieces / area. The carrier concentration was 5.50 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.38. Further, the radius of curvature in the [1-100] direction of the main surface was 18.5 m, and the first deviation angle in the [1-100] direction of the main surface was 0.05 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 22.0 m, and the second deviation angle in the [11-20] direction of the main surface was 0.05 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.00 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.2 μm. The second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 24.4 μm. For this reason, the size of one low dislocation density crystal region was 1993.4 μm × 1987.8 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In order to increase the carrier concentration of the epitaxial layer, a thickness is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above in the same manner as in Example B1, except that the epitaxial layer is intentionally doped with Si. A GaN crystal substrate with a semiconductor epitaxial layer on which a 5 μm thick GaN layer (Group III nitride semiconductor epitaxial layer 30) was formed was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 1.80 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 1.00 × 10 ¹⁷ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 193.4 μm × 1987.8 μm was obtained. The obtained chipped SBD has a C / F ratio of 0.38, a breakdown voltage yield of 0.82, an average on-resistance of 1.02 mΩ · cm ² , and a maximum on-resistance of 1.48 mΩ. • cm ² and the maximum operating current was 10A. The results are summarized in Table 7.

(Example B24)
1. Preparation of GaN Crystal Substrate A GaN crystal substrate was obtained in the same manner as in Example B4, except that a GaAs substrate having a diameter of 4 inches (10.16 cm) was used for the growth of the GaN crystal.

The obtained GaN crystal substrate has a plane orientation of (0001) on the principal surface, and the dislocation densities of the low dislocation density crystal region and the high dislocation density crystal region are 1.55 × 10 ⁵ cm ⁻² and 8.50 ×, respectively. It was 10 ⁸ cm ^-2. Further, since the number of dislocation concentration regions per 20 mm square is 12 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per dislocation density crystal region is 0. 12 / area. The carrier concentration was 6.10 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.36. Moreover, the curvature radius in the [1-100] direction of the main surface was 19.0 m, and the first deviation angle in the [1-100] direction of the main surface was 0.10 °. Further, the radius of curvature of the main surface in the [11-20] direction was 18.5 m, and the second deviation angle of the main surface in the [11-20] direction was 0.12 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.02 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.4 μm. Further, the second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 26.2 μm. Therefore, the size of one low dislocation density crystal region was 19933.3 μm × 1986.9 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In order to increase the carrier concentration of the epitaxial layer, a thickness is formed on the main surface 20m of the GaN crystal substrate 20p prepared as described above in the same manner as in Example B1, except that the epitaxial layer is intentionally doped with Si. A GaN crystal substrate with a semiconductor epitaxial layer on which a 5 μm thick GaN layer (Group III nitride semiconductor epitaxial layer 30) was formed was obtained.

In the obtained GaN layer (Group III nitride semiconductor epitaxial layer 30), the epitaxial abnormal growth region 30ei was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 30k and the high dislocation density epitaxial crystal region 30h are 1.55 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p. The carrier concentration was 2.20 × 10 ¹⁶ cm ⁻³ .

3. Production of Semiconductor Device In the same manner as in Example B1, an SBD (chip-formed semiconductor device 40c) having a Schottky electrode diameter of 1600 μm and chipped to a size of 1993.3.3 μm × 1986.9 μm was obtained. The resulting chipped SBD is C / F ratio is 0.36, the breakdown voltage yield is 0.79, the average on-resistance is 0.89mΩ · cm ^2, the maximum on-resistance 1.39mΩ • cm ² and the maximum operating current was 10A. The results are summarized in Table 7.

Referring to Table 7, in the semiconductor device (SBD), when the carrier concentration of the GaN layer (group III nitride semiconductor epitaxial layer 30) is changed, the carrier concentration is low (for example, 5.00 × 10 ¹⁴ cm ⁻³ or less). The average on-resistance and the maximum on-resistance are increased because the resistance of the epitaxial layer is increased, and the resistance of the epitaxial layer is increased when the carrier concentration is high (for example, 1.00 × 10 ¹⁷ cm ⁻³ or more). On-resistance and maximum on-resistance increased.

[Example C]
Next, as Example C, referring to FIGS. 17 to 19, group III nitride semiconductor epitaxial layer 70 is grown on main surface 20 m of GaN crystal substrate 20 p to form a GaN crystal substrate with a semiconductor epitaxial layer. Further, the p-side electrode 81 is formed on the main surface 70m of the group III nitride semiconductor epitaxial layer 70, and the n-side electrode 82 is formed on the main surface 20n of the GaN crystal substrate 20p, so that the semiconductor devices 80 and 80c are formed. The manufactured embodiment will be described. Example C includes the following Example Comparative Example RC1.

(Example C1)
1. Preparation of GaN crystal substrate A GaN crystal substrate similar to Example B4 was prepared.

The prepared GaN crystal substrate has a plane orientation of (0001) on the principal surface, and the dislocation densities of the low dislocation density crystal region and the high dislocation density crystal region are 2.10 × 10 ⁵ cm ⁻² and 8.50 × 10 respectively. It was ⁸ cm ^-2 . Further, since the number of dislocation concentration regions per 20 mm square is 13 and the number of low dislocation density crystal regions per 20 mm square is 100, the density of dislocation concentration regions per one dislocation density crystal region is 0. 13 / area. The carrier concentration was 5.00 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.38. Moreover, the curvature radius in the [1-100] direction of the main surface was 18.4 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 17.5 m, and the second deviation angle in the [11-20] direction of the main surface was 0.06 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.00 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.4 μm. Further, the second stripe crystal region of the high dislocation density crystal region on the main surface had a pitch P ₂ of 2000 μm and a width W ₂ of 26.2 μm. Therefore, the size of one low dislocation density crystal region was 19933.3 μm × 1986.9 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
Referring to FIGS. 17 to 19, an n-type GaN layer having a thickness of 2 μm is formed by MOCVD as at least one group III nitride semiconductor epitaxial layer 70 on main surface 20 m of prepared GaN crystal substrate 20 p. 71, a triple well in which an n-type Al _0.1 Ga _0.9 N layer 72 having a thickness of 0.01 μm and a GaN barrier layer having a thickness of 15 nm and an In _0.15 Ga _0.85 N well layer having a thickness of 3 nm are alternately stacked as the light emitting layer 73. An MQW (multiple quantum well) structure layer having a structure, a p-type Al _0.1 Ga _0.9 N layer 74 having a thickness of 0.01 μm, and a p-type GaN layer 75 having a thickness of 0.1 μm were sequentially grown. Thus, a semiconductor epitaxial layer-attached GaN crystal substrate in which the group III nitride semiconductor epitaxial layer 70 was formed on the main surface 20m of the GaN crystal substrate 20p was obtained.

In the obtained group III nitride semiconductor epitaxial layer 70, an epitaxial abnormal growth region was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 70k and the high dislocation density epitaxial crystal region 70h are 2.10 × 10 ⁵ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p.

3. Next, the p-type GaN layer 75 (the uppermost layer of the group III nitride semiconductor epitaxial layer 70) in the region 80k immediately above and immediately below the low dislocation density crystal region 20k of the GaN crystal substrate 20p is formed. A p-side electrode 81 was formed on the main surface 70m as follows. A transparent electrode 81a, which is a part of the p-side electrode 81, was vapor-deposited with a nickel layer having a thickness of 5 nm and a gold layer having a thickness of 10 nm by a resistance heating method, and the metal layer was lifted off. Thereafter, as a terminal electrode 81b which is a part of the p-side electrode 81, an Au layer having a diameter of 100 μm and a thickness of 300 nm was formed by resistance heating, and wire bonding was performed. Next, in the region 80k immediately above and directly below the low dislocation density crystal region 20k of the GaN crystal substrate 20p and on the other main surface 20n of the GaN crystal substrate 20p, as the n-side electrode 82, a vacuum deposition method (more Specifically, a 20 nm-thick Ti layer and a 300 nm-thick Al layer were formed on the entire main surface 20n by the EB method to obtain the wafer-like LED (wafer-like semiconductor device 80).

  Next, in the wafer-like LED (wafer-like semiconductor device 80), the GaN crystal substrate 20p, the group III nitride semiconductor epitaxial layer 70, the p-side electrode 81, and the n-side electrode 82 constituting each LED are all GaN. Wafer so that it falls within the region 80k immediately above and directly below the low dislocation density crystal region 20k of the crystal substrate 20p, and the main surface of the chipped SBD after division is substantially square and its area is maximized. LED (wafer-like semiconductor device 80) was divided by a dividing line 80b to obtain an LED (chip-formed semiconductor device 80c) having a chip size of 19933.3 μm × 1986.9 μm.

The obtained chip-formed LED had a C / F ratio of 0.38, a high emission wavelength distribution yield of 0.97, and a small increase in voltage during operation of 0.04V. Here, the emission wavelength distribution yield was calculated as follows. In the above-mentioned wafer-like LED, the light output of the LED located within a radius of 20 mm from the center of the GaN crystal substrate is measured with a multichannel spectrometer when the current of 75 A / cm ² is applied in the integrating sphere, The average value Av and standard deviation σ were calculated. Thereafter, the emission wavelengths of all the LEDs formed into chips from the wafer-like LED are measured, and the LED whose measured value A satisfies | A−Av | ≦ σ is acceptable, and | A−Av |> σ The yield rate (non-defective product) / (non-defective product + defective product) was calculated using the LED to be satisfied as a defective product. Further, the amount of voltage increase during operation was calculated as follows. With respect to the obtained chip-formed LED, the voltage at the time of operation necessary to pass a current of 100 mA at an ambient temperature of 80 ° C. is measured at the start of operation and at the time of operation for 1000 hours. The amount of increase in voltage was calculated. The results are summarized in Table 8.

(Comparative Example RC1)
1. Preparation of GaN Crystal Substrate A GaN crystal substrate similar to Comparative Example RB2 was prepared.

The prepared GaN crystal substrate has a principal plane with a plane orientation of (0001), and the dislocation densities of the low dislocation density crystal region and the high dislocation density crystal region are 8.20 × 10 ⁶ cm ⁻² and 8.50 × 10 respectively. It was ⁸ cm ^-2 . Further, since the number of dislocation concentration regions per 20 mm square is 705 and the number of low dislocation density crystal regions per 20 mm square is 10, the density of dislocation concentration regions per one dislocation density crystal region is 70. 5 / area. Here, from the same viewpoint as the comparative example RB1, one low dislocation density crystal region of this comparative example corresponds to ten low dislocation density crystal regions in the examples. That is, since the number of low dislocation density crystal regions corresponding to the example per 20 mm square is 100, the density of dislocation concentration regions per one example equivalent dislocation density crystal region was 7.05 / region. . The carrier concentration was 5.20 × 10 ¹⁸ cm ⁻³ and the C / F ratio was 0.61. Further, the radius of curvature in the [1-100] direction of the main surface was 18.9 m, and the first deviation angle in the [1-100] direction of the main surface was 0.06 °. Moreover, the curvature radius in the [11-20] direction of the main surface was 5.1 m, and the second deviation angle in the [11-20] direction of the main surface was 0.20 °. Therefore, the difference between the first deviation angle and the second deviation angle was 0.14 °. The first stripe crystal region of the high dislocation density region on the main surface had a pitch P ₁ of 2000 μm and a width W ₁ of 13.2 μm. For this reason, the size of one low dislocation density crystal region at 20 mm square was 1993.4 μm × 20000 μm.

2. Growth of group III nitride semiconductor epitaxial layer (production of GaN crystal substrate with semiconductor epitaxial layer)
In the same manner as in Example 1C, a GaN crystal substrate with a semiconductor epitaxial layer in which a group III nitride semiconductor epitaxial layer 70 was formed on the main surface 20m of the GaN crystal substrate 20p was obtained.

In the obtained group III nitride semiconductor epitaxial layer 70, an epitaxial abnormal growth region was not formed. In the GaN layer, the dislocation densities of the low dislocation density epitaxial crystal region 70k and the high dislocation density epitaxial crystal region 70h are 8.20 × 10 ⁶ cm ⁻² and 8.50 × 10 ⁸ cm ⁻² , respectively. It was equivalent to the dislocation density of the low dislocation density crystal region 20k and the high dislocation density crystal region 20h of the GaN crystal substrate 20p.

3. Production of Semiconductor Device Next, a wafer-like LED was produced in the same manner as in Example C1, and a chip-formed LED was obtained. The obtained chip-formed LED had a C / F ratio of 0.61, an emission wavelength distribution yield of 0.75, and an increase in voltage during operation of 1.09 V. The results are summarized in Table 8.

  Referring to Table 8, the LED obtained in Example C1 had a higher emission wavelength distribution yield and a lower voltage increase during operation than the LED obtained in Comparative Example RC1. This is because the first shift angle and the second shift angle of the GaN crystal substrate of the former LED are smaller than the first shift angle and the second shift angle of the GaN crystal substrate of the latter LED, respectively. It is considered that the group III nitride semiconductor epitaxial layer 70 having a uniform carrier concentration and a uniform carrier concentration is formed when the semiconductor epitaxial layer 70 is grown.

  In addition, in describing the examples and comparative examples of the present application, the experimental data was first summarized in Tables 1 to 8, and then referring to the numerical values in Tables 1 to 8. That is, the numerical values of the experimental data described in Tables 1 to 8 and the specification are the original numerical values of the experimental data described in the table.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 10 Base substrate, 10m, 20m, 20n, 30m, 70m Main surface, 11 mask, 11s 1st stripe mask, 11t 2nd stripe mask, 11w opening part, 12 additional mask, 12w micro opening part, 20 GaN crystal, 20b crystal Growth start plane, 20c (0001) plane, 20d (000-1) plane, 20f facet, 20h high dislocation density crystal region, 20hs first stripe crystal region, 20ht second stripe crystal region, 20k low dislocation density crystal region, 20kc (0001) plane growth crystal region, 20kd dislocation concentration region, 20kf facet growth crystal region, 20p GaN crystal substrate, 30,70 group III nitride semiconductor epitaxial layer, 30ei epitaxial abnormal growth region, 30h, 70h, 71h, 72h, 73h , 74h, 75h High dislocation Epitaxial crystal region, 30k, 70k, 71k, 72k, 73k, 74k, 75k low dislocation density epitaxial crystal region, 33 GaN crystal substrate with semiconductor epitaxial layer, 40, 40c, 80, 80c semiconductor device, 40b, 80b dividing line, 40k, just above and just below the region of 80k low dislocation density crystal region, 41 Schottky electrode, 41a first layer, 41b second layer, 42 ohmic electrode, 71 n-type GaN layer, 72 n-type Al _0.1 Ga _0.9 n Layer, 73 light emitting layer, 74 p-type Al _0.1 Ga _0.9 N layer, 75 p-type GaN layer, 81 p-side electrode, 81a transparent electrode, 81b terminal electrode, 82 n-side electrode.

Claims (14)

A main surface having an off angle of 0 ° to 30 ° with respect to the (0001) plane;
Including a low dislocation density crystal region and a high dislocation density crystal region,
The high dislocation density crystal region on the main surface has a lattice shape including a plurality of first stripe crystal regions extending in the [1-100] direction and a plurality of second stripe crystal regions extending in the [11-20] direction. A GaN crystal substrate. The first stripe crystal region has a width of 5 μm to 120 μm and a pitch of 200 μm to 10000 μm,
2. The GaN crystal substrate according to claim 1, wherein the second stripe crystal region has a width of 5 μm to 120 μm and a pitch of 200 μm to 10,000 μm.   3. The GaN crystal substrate according to claim 1, wherein the high dislocation density crystal region is a polarity inversion crystal region in which the polarity in the [0001] direction is inverted with respect to the low dislocation density crystal region. The low dislocation density crystal region includes a (0001) plane growth crystal region and a facet growth crystal region,
The GaN crystal substrate according to any one of claims 1 to 3, wherein a ratio of an area of the (0001) plane growth crystal region to an area of the facet growth crystal region is 0.7 or less on the main surface.   A first shift angle that is a difference between an off angle at the center of the main surface and an off angle at an end in the [1-100] direction from the center, and an off angle at the center of the main surface and the center from the center [11 −20] the second deviation angle that is the difference between the off-angle at the end in the direction is 0 ° or more and 0.30 ° or less, and the difference between the first deviation angle and the second deviation angle is 0 The GaN crystal substrate according to any one of claims 1 to 4, wherein the GaN crystal substrate has an angle of from 0 ° to 0.30 °.   The GaN crystal substrate according to any one of claims 1 to 5, wherein the first stripe crystal region or the second stripe region is discontinuous at least at one place. The GaN crystal substrate according to any one of claims 1 to 6, wherein the carrier concentration is 1 × 10 ¹⁸ cm ⁻³ or more and 1.2 × 10 ¹⁹ cm ⁻³ or less.   The low dislocation density crystal region has a dislocation concentration region of 0.1 / region to 5.5 / region per region surrounded by the high dislocation density crystal region. The GaN crystal substrate according to any one of the above. A method for producing a GaN crystal substrate according to any one of claims 1 to 8,
Preparing the base substrate having a main surface having an off angle of 0 ° or more and 30 ° or less with respect to the plane orientation of the base substrate corresponding to the (0001) plane of the GaN crystal substrate;
A plurality of first stripe masks extending in a first direction corresponding to the [1-100] direction of the GaN crystal substrate and a [11-20] direction of the GaN crystal substrate on the main surface of the base substrate. Forming a mask having a lattice pattern including a plurality of second stripe masks extending in a second direction;
Growing a GaN crystal on a main surface of the base substrate on which the mask is formed;
Forming a main surface parallel to the main surface of the base substrate on the GaN crystal to obtain the GaN crystal substrate, and
In the step of growing the GaN crystal, the GaN crystal grows (000-1) plane on the mask, and the GaN crystal grows (0001) plane in the center of the opening of the mask of the base substrate. The GaN crystal is faceted in the periphery of the opening of the mask,
A GaN crystal on which the GaN crystal grows including the low dislocation density crystal region formed by the (0001) plane growth and the facet growth and the high dislocation density crystal region formed by the (000-1) plane growth. A method for manufacturing a substrate.   10. The method of manufacturing a GaN crystal substrate according to claim 9, wherein the first stripe mask or the second stripe mask is discontinuous at least at one location. A GaN crystal substrate according to any one of claims 1 to 8, and at least one group III nitride semiconductor epitaxial layer formed on a main surface of the GaN crystal substrate,
The group III nitride semiconductor epitaxial layer includes a low dislocation density epitaxial crystal region formed immediately above the low dislocation density crystal region of the GaN crystal substrate, and a direct upper side of the high dislocation density crystal region of the GaN crystal substrate. And a high dislocation density epitaxial crystal region formed on the GaN crystal substrate with a semiconductor epitaxial layer. The GaN crystal substrate according to any one of claims 1 to 8, at least one group III nitride semiconductor epitaxial layer formed on one main surface of the GaN crystal substrate, and the group III nitride An electrode formed on at least one of the main surface of the semiconductor epitaxial layer and the other main surface of the GaN crystal substrate,
The GaN crystal substrate is a semiconductor device having a size of 400 μm square or more and a dislocation density of less than 1 × 10 ⁷ cm ⁻² . The GaN crystal substrate includes a (0001) plane growth crystal region and a facet growth crystal region,
13. The semiconductor according to claim 12, wherein a ratio of an area of the (0001) plane growth crystal region to an area of the facet growth crystal region is 0.2 or more and 0.7 or less on one main surface of the GaN crystal substrate. device. Preparing a GaN crystal substrate according to any one of claims 1 to 8,
A step of growing at least one group III nitride semiconductor epitaxial layer on one main surface of the GaN crystal substrate, and a region immediately above and immediately below a low dislocation density crystal region of the GaN crystal substrate, Forming an electrode on at least one of the main surface of the group III nitride semiconductor epitaxial layer and the other main surface of the GaN crystal substrate.

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