JP2005302980A - Nitride based semiconductor light emitting element and its fabrication process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nitride based semiconductor light emitting element enhancing emission efficiency while having a semiconductor with little dislocation, and also to provide its fabrication process. <P>SOLUTION: A first nitride based semiconductor light emitting element is composed of a group III nitride based compound represented by Al<SB>x</SB>Ga<SB>y</SB>In<SB>1-x-y</SB>N (where, 1≥x≥0, 1≥y≥0, 1≥x+y≥0) and comprises a substrate, a semiconductor layer formed on the substrate including a first semiconductor layer, an active layer formed on the first semiconductor layer, and a second semiconductor layer formed on the active layer and provided with a recess parting at least the active layer from the upper surface in the direction perpendicular to the substrate, and a transparent insulator formed in the recess of the semiconductor layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a nitride-based semiconductor light-emitting device and a method for manufacturing the same, and more particularly, to a nitride-based semiconductor light-emitting device having improved luminous efficiency using light reflection from a light-emitting layer and a method for manufacturing the same.

  Group III nitride compounds are direct transition semiconductors with a wurtzite structure in the stable phase, and the forbidden band width can be changed from 6.2 eV for AlN to 1.9 eV for InN. It has been attracting attention as a material for light emitting devices in the ultraviolet region, and semiconductor light emitting devices using Group III nitride compounds are being developed.

Among such group III nitride compounds, the general formula is Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0). AlGaInN-based compounds have been developed as light-emitting / light-receiving device materials for visible light because the emission wavelength can be changed from ultraviolet to red according to the mixed crystal ratio. In particular, further research has been actively conducted on the occasion that blue and green high-intensity light-emitting diodes using gallium nitride (GaN) compounds have been realized. In addition, the AlGaN compound in which x + y = 1 in the above general formula is a semiconductor that is stable even at a high temperature of 500 ° C. or higher, and therefore, development is also underway as a device material in a high temperature environment or without cooling.

Here, a general method for manufacturing a semiconductor light emitting device using a group III nitride compound represented by the general formula Al _x Ga _y In _1-xy N uses a sapphire single crystal for a crystal substrate. In addition, various GaN-based crystal layers are grown by epitaxial growth via a buffer layer thereon, and a desired GaN-based crystal layer is used as a light-emitting portion. Of the compounds represented by the general formula Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0), GaN has a bulk crystal synthesis. This is because it is extremely difficult.
However, the difference in lattice constant between the sapphire substrate and GaN is as large as about 16%, and the defect density in the growth layer reaches 10 ⁶ to 10 ⁹ cm ⁻² . In the GaN-based crystal layer grown by such a method, dislocations due to lattice mismatch with the crystal substrate exist at high density.

  That is, the sapphire substrate and gallium nitride have different physical properties such as not only a lattice constant but also a different thermal expansion coefficient, so that a large amount of crystal defects called dislocations are generated. Dislocations are inherited upwards even when the GaN-based crystal grows and increases in thickness, resulting in continuous defect portions called dislocation lines (threading dislocations), which degrades the device characteristics, such as reducing the life of the blue-violet laser. It will be.

  Although the device operates at such a high defect density, it has high quality and high reliability, although it has a peculiar characteristic of a semiconductor based on a group III nitride compound that the luminous efficiency does not drop significantly even if the defect density is high. In order to obtain a reliable device, it is essential to reduce the defect density. In order to avoid this, there is a method of obtaining a low dislocation GaN-based crystal using a mask layer (see, for example, Patent Document 1).

According to this, if the semiconductor layer has a certain thickness in the process of growing as a semiconductor layer, the dislocation flows in the lateral direction, so that a lower dislocation semiconductor layer is formed. On the other hand, after growing the semiconductor layer, it is necessary to provide an active layer to function as a semiconductor light emitting element, and the surface of the active layer becomes a light emitting region (see, for example, Patent Document 2).
JP 2000-91253 A JP 2002-184707 A

  However, even if the light emitting element is configured by improving the semiconductor layer to reduce dislocations, it cannot emit light brighter than the amount of light emitted from the active layer. Therefore, there has been a demand for a nitride-based semiconductor light-emitting device having excellent light emission efficiency and a manufacturing method thereof by a semiconductor layer formed with fewer dislocations.

The first nitride semiconductor light emitting device according to the present invention is represented by Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0). A nitride-based semiconductor light-emitting device comprising a group III nitride-based compound, comprising: a substrate; and a semiconductor layer formed on the substrate, wherein the first semiconductor layer and the first semiconductor layer A semiconductor layer including a formed active layer and a second semiconductor layer formed on the active layer, the semiconductor layer including a recess that divides at least the active layer in a direction perpendicular to the substrate from the upper surface; and the semiconductor layer And a transparent insulator formed in the recess.

  The second nitride semiconductor light emitting device according to the present invention includes a buffer layer formed on the substrate and a mask formed on the buffer layer between the substrate and the first semiconductor layer. A mask layer including a contact portion that contacts a part of the surface of the buffer layer and the first semiconductor layer, and a mask portion that prevents contact between the buffer layer and the first semiconductor layer; ,including.

  In this case, the contact portion of the mask layer may have a substantially hexagonal shape when viewed from a direction perpendicular to the substrate. Moreover, the element provided with the transparent electrode layer on the said semiconductor layer may be sufficient.

The first nitride-based semiconductor light-emitting device manufacturing method according to the present invention includes Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0). A method for producing a nitride-based semiconductor light-emitting device comprising a group III nitride-based compound represented by: a substrate processing step for performing a process for partially forming a first semiconductor layer on a substrate; Forming a first semiconductor layer on the treated substrate by epitaxial growth; forming an active layer on the upper surface of the first semiconductor layer; and forming a second semiconductor layer on the active layer by epitaxial growth And a step of forming a transparent insulator in a portion where the first semiconductor layer, the active layer, and the second semiconductor layer are not formed.

  The substrate processing step includes a step of forming a buffer layer formed on the substrate between the substrate and the first semiconductor layer, a part of the surface of the buffer layer on the buffer layer, and the The method may include a step of forming a mask layer including a contact portion that makes contact with the first semiconductor layer and a mask portion that prevents contact between the buffer layer and the first semiconductor layer.

  In this case, the contact portion of the buffer layer may have a substantially hexagonal shape when viewed from a direction perpendicular to the substrate.

  The substrate processing step may include a step of performing mask patterning on the substrate and a step of half-etching the substrate.

  Further, the substrate processing step includes a step of forming a buffer layer for forming the first semiconductor layer on the substrate, and a step of forming a convex portion on a part of the buffer layer. But you can.

  The second semiconductor layer after the growth is etched between the step of forming the second semiconductor layer on the active layer by epitaxial growth and the step of forming a transparent insulator in the recess of the semiconductor layer. The method may further include a step of flattening the upper portion.

  Furthermore, a step of providing a transparent electrode layer on the second semiconductor layer and the transparent insulator may be included.

  Meanwhile, after the step of forming the transparent insulator, a step of flattening the upper portion of the grown second semiconductor layer and the insulator by etching may be included. In this case, the upper portion is flattened. After the step of forming, a step of providing a transparent electrode layer on the second semiconductor layer and the transparent insulator may be included.

  As described above, according to the present invention, the light emission efficiency can be increased while having a semiconductor layer with few dislocations.

(Embodiment 1)
Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a group III nitride compound represented by Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0) according to the present invention. 1 is a diagram showing a nitride-based semiconductor light-emitting element 10 made of FIG. 1 shows a nitride-based semiconductor light emitting device 10 including a transparent insulator 22 formed in a recess of a semiconductor layer.

  In FIG. 1, a substrate 12, a semiconductor layer 20 formed on the substrate, a first semiconductor layer 14, an active layer 16 formed on the first semiconductor layer, and an active layer are formed. A semiconductor layer 20 having a recess that divides at least the active layer 16 in a direction perpendicular to the substrate from the upper surface, and a transparent insulator 22 formed in the recess of the semiconductor layer 20. A nitride-based semiconductor light emitting device 10 is illustrated.

In FIG. 1, for example, sapphire (Al ₂ O ₃ ) is used for the substrate 12. Since the dissociation pressure of nitrogen is high, bulk crystal growth with GaN is difficult, so it is difficult to use a GaN substrate. If the substrate is made of a material different from GaN, it is limited to sapphire. For example, SiC, Si, GaAs, or the like can be used, but the present invention is not limited to this.

  Reference is now made to FIG. In FIG. 11, 51 is sapphire, 52 is a buffer layer, and 53 is a GaN layer. FIG. 11 is a diagram illustrating what is generally called a “substrate”. In general, the term “substrate” may have a plurality of meanings, so the meaning of “substrate” in this specification will be clarified here. FIG. 11A illustrates a “substrate” as used in this specification. In FIG. 11, sapphire 51 is illustrated as an example among the above examples as the substrate. FIG. 11B illustrates a sapphire substrate provided with a buffer layer 52. In general, the entire two-layer structure may be referred to as a “substrate” as a whole. FIG. 11C illustrates a substrate in which a thin GaN layer 53 is provided on the upper surface of FIG. Again, this three-layer structure is generally sometimes referred to as a “substrate” as a whole.

  Thus, in general, when simply referred to as “substrate”, the two-layer structure or the three-layer structure illustrated in FIG. 11B or FIG. 11C may be generally referred to as “substrate”. The “substrate” mentioned in the document is only the substrate illustrated in FIG. 11A, that is, the buffer layer 52 or GaN on the sapphire substrate 51 as shown in FIGS. 11B and 11C. The structure in which even the layer 53 is formed is not included in the concept of “substrate”.

  Therefore, as described above, the expression “buffer layer 24 formed on the substrate 12” means the state of FIG. 11B in FIG.

  Here, for a sapphire substrate, it is usually not possible to form a bulk crystal of GaN as it is, but if difficult, a semiconductor layer is formed on the substrate in order to form the first semiconductor layer 14. It is necessary to carry out a process for forming.

  As a process for forming a semiconductor layer on the substrate, for example, a GaN layer having a thickness of several μm is formed on the surface of the substrate made of sapphire by low temperature growth, or an AlGaN layer having a thickness of several tens of nm. This is realized by forming a GaN layer having a thickness of several μm by low-temperature growth after the formation. That is, when the substrate is in a state as shown in FIG. 11B or FIG. 11C, it becomes easier to form the semiconductor layer.

  In this specification, the state shown in FIG. 11B or FIG. 11C does not mean a single “substrate” as a whole, but performs a process for forming a semiconductor layer. It is grasped as a substrate.

  As for this buffer layer, if there is a layer located between the “substrate” in this specification and a mask layer or a semiconductor layer described later, the layer can be grasped as a buffer layer. As described above, the buffer layer may be made of GaN.

  However, in this specification, even if the state in which the semiconductor layer is directly formed on the substrate is shown, it does not exclude that the process for forming the semiconductor layer on the substrate is being performed. It is.

  FIG. 1 illustrates that a semiconductor layer 20 including a first semiconductor layer 14, an active layer 16, and a second semiconductor layer 18 formed on the substrate 12 is included. Epitaxial growth can be used to form the first semiconductor layer 14 shown in FIG.

  Epitaxial growth refers to growing a semiconductor layer as a thin film crystal having the same crystal structure and crystal orientation as a substrate on a base crystal substrate. There is a method of growing a bulk crystal from a melt for producing a single crystal. However, since GaN has a very high melting point and an extremely high equilibrium vapor pressure of nitrogen, it is difficult to grow by this method. It is necessary to use epitaxial growth for crystal growth.

  The semiconductor mixed crystal crystal growth methods can be broadly classified into liquid phase epitaxial growth, vapor phase epitaxial growth, and molecular beam epitaxial growth. Liquid phase epitaxial growth is a crystal growth method in which growth proceeds in the form of precipitation of crystals from a supersaturated solution while substantially maintaining an equilibrium state between the solid phase and the liquid phase. Vapor phase epitaxial growth is a crystal growth method in which crystal growth is performed under a pressure of several Torr to atmospheric pressure while flowing a source gas. In molecular beam epitaxy (MBE), molecules or atoms of growth crystal elements are supplied to the substrate by flying in an ultra-high vacuum, and these molecules or atoms reach the substrate as a molecular beam with almost no collision. This is a crystal growth method for promoting crystal growth.

  Among these epitaxial growths, there are particularly excellent ones such as a halide vapor phase growth method (HVPE method), a molecular beam epitaxy method (MBE method), and a metal organic chemical vapor deposition method (MOCVD method). The epitaxial growth used as the form may be any one of the above-mentioned various crystal growth methods.

The first semiconductor layer 14 is formed by epitaxially growing a layer made of GaN as described above. However, it is not limited to GaN, but is a group III nitride-based compound having a general formula of Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0) As long as it is a nitride compound represented by (), a compound having an arbitrary composition ratio may be used.

FIG. 1 further shows an active layer 16 formed on the first semiconductor layer 14. The active layer 16 is made of various Group III nitride compounds represented by, for example, Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0). It can be combined but is not limited to this.

  In FIG. 1, a second semiconductor layer 18 is illustrated on the active layer 16. The second semiconductor layer 18 is a semiconductor layer that conducts a carrier having a polarity opposite to that of the carrier conducted by the first semiconductor layer 14 and has a sandwich structure in which the active layer 16 is sandwiched between the two semiconductor layers.

  FIG. 1 shows that the semiconductor layer 10 has a recess. This concave portion is formed from the upper surface toward the substrate vertical downward direction, and divides the active layer 16. The recess can be formed by applying a resist film on the second semiconductor layer 18 other than the portion to be the recess and using a photolithography method, a wet etching method, or the like.

FIG. 1 shows a transparent insulator 22 formed in a semiconductor layer 10 having a recess. For the insulator 22, a transparent insulator such as SiO ₂ or SiN is used. In forming the insulator 22, an SOG (Spin on Glass) method can be used. Here, according to the SOG method, for example, a transparent insulator such as liquid glass is applied by a centrifugal force of rotation, and, for example, a solution in which a silicate compound as an SOG material is dissolved in an organic solvent is applied and then baked. Thus, an insulator mainly composed of SiO ₂ can be formed in the recess.

  In FIG. 1, a metal such as Al or ZnO is further used on the semiconductor layer 20 to form a transparent electrode. It is optional to provide a contact layer (not shown) when depositing the metal.

FIG. 2 shows a group III nitride compound represented by Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0) according to the present invention. 1 is a diagram showing a nitride-based semiconductor light-emitting element 10 made of In addition, the same code | symbol as FIG. 1 has the same meaning. In addition, the semiconductor layer 20 is configured by the first semiconductor layer 14, the active layer 16, the second semiconductor layer 18, and the insulator 22 as in FIG.

  FIG. 2 shows a buffer layer 24 formed on the substrate 12 between the substrate 12 and the first semiconductor layer 14, and a mask layer 26 formed on the buffer layer 24. A group III nitride comprising a mask layer 26 comprising a contact portion 28 for contacting a part of the first semiconductor layer 14 with the first semiconductor layer 14 and a mask portion 32 for preventing the buffer layer and the first semiconductor layer 14 from contacting each other. A nitride-based semiconductor light-emitting device 10 made of a base compound is illustrated.

  The buffer layer 24 formed on the substrate 12 is formed on the buffer layer 24 and between the first semiconductor layer 14 and a part of the surface of the buffer layer 24 and the first semiconductor layer are in contact with each other. And a mask portion 32 for preventing contact between the contact portion 28 and the buffer layer and the first semiconductor layer.

  The substrate 12 on which the buffer layer 24 is formed means the state illustrated in FIG. Therefore, it is needless to say that the substrate 12 includes a state where some processing is performed to form the buffer layer 24. For example, as the buffer layer 24, an AlGaN layer (not shown) having a thickness of several tens of nm is formed on the surface of the substrate 12 made of sapphire, and then a GaN layer is formed with a thickness of several μm by low temperature growth. It may be realized by doing so. Furthermore, it is a matter of course that a state in which some processing is performed on the buffer layer 24 is included.

  The contact portion 28 makes a part of the surface of the buffer layer 24 and the first semiconductor layer 14 contact each other. The mask portion 32 prevents contact between the buffer layer 24 and the first semiconductor layer 14.

For example, SiO ₂ or SiN can be used for the mask layer 26. First, SiO ₂ or SiN is applied to the surface of the buffer layer 24, and a resist film is further applied. For example, a mask portion 32 that restricts the growth region of the first semiconductor layer 14 using a photolithography method and a wet etching method. Is formed by patterning to form the mask layer 26. Here, the thickness of the mask layer 26 is preferably 0.1 μm to 10 μm, but is not limited thereto. In this patterning, a pattern composed of the mask portion 32 and the contact portion 28 in the mask layer 26 is formed. Although this pattern is arbitrary, for example, the contact portion 28 may be configured to be a circular recess, or the contact portion 28 may be configured to be a hexagonal recess.

  Reference is now made to FIG. FIG. 3 illustrates the nitride semiconductor light emitting device 10 having a substantially hexagonal shape when the contact portion 28 of the mask layer 26 is viewed from a direction perpendicular to the substrate 12. In FIG. 3, the same reference numerals as those in FIG. FIG. 3A shows a state in which a hexagonal concave portion is formed as the contact portion 28 from the mask layer 26 using the above-described method such as etching. 3B is a plan view of FIG. 3A, and FIG. 3C is a cross-sectional view of A-A ′ in FIG. 3A. When the first semiconductor layer 14 is formed by using the hexagonal shape, the stable phase of the group III nitride compound is a direct transition semiconductor having a wurtzite structure having a hexagonal column shape. Can be made faster.

  FIG. 4 is a diagram in which the nitride semiconductor light emitting device 10 according to the present invention is configured as an LED. The same reference numerals as those in FIG. 1 or 2 represent the same meaning, and an n-electrode 66 is formed in the semiconductor layer 14.

FIG. 4 shows a nitride formed of a group III nitride compound represented by Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0). A physical semiconductor light emitting device 10 is shown. In FIG. 4A, the first semiconductor layer 14, the active layer 16, and the second semiconductor layer 18 are formed on the substrate 12, and the first semiconductor layer 14, the active layer 16, and the second semiconductor layer 18 are formed. The semiconductor layer 20 including the semiconductor layer 18 is included in the same manner as shown in FIG. As shown in FIG. 4B, the substrate 12 is formed with a buffer layer for forming the semiconductor layer 20, and a mask layer 26 including a contact portion and a mask portion is formed on the buffer layer. It may be a substrate.

4 (1) and 4 (2), for example, the first semiconductor layer 14 is an n-type semiconductor (n-GaN) made of GaN, and the second semiconductor layer 18 is made of GaN. P-type semiconductor (p-GaN). The first semiconductor layer 14 and the second semiconductor layer 18 are represented by Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0). It consists of a group III nitride compound and may be a single layer or multiple layers. The active layer 16 is made of a compound made of, for example, GaInN, but is not limited thereto.

In forming the first semiconductor layer 14 or the second semiconductor layer 18, for example, Si, Mg, Zn can be used as a dopant. The first semiconductor layer 14 is formed by using GaN grown at a low temperature on the substrate 12 made of sapphire as a buffer layer 24 and using SiO ₂ or SiN by a sputtering method, a CVD method, a vapor deposition method, etc. After the mask layer 26 including the contact portion 28 is formed by etching, it is formed by epitaxial growth. An n-electrode 66 is formed on the semiconductor layer 14 made of n-GaN, and a p-electrode 34 is formed on the semiconductor layer 18 made of p-GaN.

  Please refer to FIG. FIG. 5 shows a nitride-based semiconductor light-emitting device made of a group III nitride-based compound according to the present invention shown in FIGS. 1 (1) and 2 as shown in FIGS. 4 (1) and 4 (2). It is a figure which shows the state of the light emission at the time of using as LED). As shown in FIG. 1B, the semiconductor layer 20 includes a first semiconductor layer 14, an active layer 16, and a second semiconductor layer 18.

  In FIG. 5, the light emitted from the active layer 16 is indicated by an arrow. The refractive index of GaN is 3.5, which is smaller than the refractive index of the transparent insulator 22. Therefore, the light transmission direction is toward the upper part of the drawing (the direction marked with A). Further, the transparent insulator 22 can transmit light reflected by the substrate 12 as a mirror surface.

As a result, it is possible to increase the luminance and obtain an LED with high luminous efficiency.
In addition, in the LED shown in FIG. 4B, by providing the mask layer 26, it is possible to obtain an LED with good luminous efficiency, which includes the high-quality semiconductor layer 20 with less dislocation.

(Embodiment 2)
6 and 7 show a group III nitride represented by Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0) according to the present invention. 1 is a diagram showing a method for manufacturing a nitride semiconductor light emitting device 10 made of a physical compound.

  6 and 7 show a substrate processing step for performing a process for partially forming the first semiconductor layer 14 on the substrate 12, and the first semiconductor layer 14 is epitaxially grown on the substrate 12 subjected to this process. The step of forming the active layer 16 on the upper surface of the first semiconductor layer, the step of forming the second semiconductor layer 18 on the active layer 16 by epitaxial growth, the first semiconductor layer 14 and the first semiconductor layer 14 A step of forming a transparent insulator 22 in a portion where the second semiconductor layer 18 is not formed is illustrated.

  FIG. 6A shows a substrate processing step for performing a process for partially forming the first semiconductor layer 14 on the substrate 12 between the substrate 12 and the semiconductor layer 20 and on the substrate 12. The process of forming the buffer layer 24 is illustrated in FIG.

  Further, in FIG. 6B, on the buffer layer 24, a contact portion 28 for bringing a part of the surface of the buffer layer 24 into contact with the first semiconductor layer 14, and the buffer layer 24 and the first semiconductor layer 14. A process of forming a mask layer 26 including a mask portion 32 that prevents contact with the mask portion 32 is illustrated.

The mask layer 26 is provided to limit the growth region of the first semiconductor layer 14. For example, SiO ₂ or SiN can be used for the mask layer 26. For the mask layer 26, first, SiO ₂ or SiN is formed on the surface of the buffer layer 24 by a sputtering method, a CVD method, a vapor deposition method or the like, and further a resist film is applied, for example, using a photolithography method and a wet etching method. It is formed by patterning. In this patterning, the pattern of the mask layer 26 can be an arbitrary shape, but may be a substantially hexagonal shape as shown in FIG.

  When the pattern of the mask layer 14 has a substantially hexagonal shape and the contact portion 28 of the buffer layer 24 has a substantially hexagonal shape when viewed from the direction perpendicular to the substrate 12, a dotted line in FIG. The first semiconductor layer 14 is formed in an angular shape or a conical shape having a triangular cross section as shown in FIG. Further, as shown by the dotted line in FIG. 6 (3), if the first semiconductor layer 14 is formed in a shape having a substantially triangular cross section such as a pyramid or a cone, the contact portion 28 can be arbitrarily formed. Shape may be sufficient. For example, a lattice shape or a mask layer having a shape that forms a hexagonal recess as the contact portion 28 may be used.

  FIG. 6 (3) shows a process of forming the first semiconductor layer 14 on the contact portion 28 by epitaxial growth. Here, the epitaxial growth is as described in (Embodiment 1). Any of the various crystal growth methods already described may be used.

The first semiconductor layer 14 in FIG. 6 (3) is formed by epitaxially growing a layer made of GaN as described above. However, it is not limited to GaN, but is a group III nitride-based compound having a general formula of Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0) As long as it is a nitride compound represented by (), a compound having an arbitrary composition ratio may be used.

  This epitaxial growth is selective lateral growth (ELO), and not only the first semiconductor layer 14 grows vertically from the contact portion 28 of the mask layer 26 but also the lateral direction in the horizontal direction of the drawing. Grows in the direction as well. As a result, as shown in FIG. 6 (4), the top of the first semiconductor layer 14 is flattened. Of course, the top of the first semiconductor layer 14 may be flattened by etching or the like in a state where the top is not flat. Further, by further growing the first semiconductor layer 14, the first semiconductor layer 14 is formed on the mask portion 32 of the mask layer 26 and the first semiconductor layer 14 is also formed on the mask portion 32. In some cases, such a situation is not excluded.

  Refer to FIG. 12 for the selected lateral growth. FIG. 12 is a diagram showing selective lateral growth by the ELO method. Here, the same reference numerals as in FIG. 2 have the same meaning as in FIG. FIG. 12A shows a mask layer 26 formed on the buffer layer 24, on which the first semiconductor layer 14 is epitaxially grown. In FIG. 12 (2), the epitaxial growth proceeds, and the first semiconductor layer 14 also grows on the mask portion 32 of the mask layer 26. At this time, epitaxial growth occurs in the lateral direction as indicated by arrows in the horizontal direction in the figure. According to this ELO method, the dislocations of the grown semiconductor layer 14 grow in the lateral direction, so that the number of dislocations near the apex is reduced.

  Then, as shown in FIG. 6 (3), the upper portion of the first semiconductor layer 14 is planarized by etching or polishing (FIG. 6 (4)), and as shown in FIG. 7 (1), the first semiconductor layer 14 is flattened. An active layer 16 is formed on the upper surface of the layer 14. Further, as shown in FIG. 7B, a second semiconductor layer 18 is formed on the active layer 16 by epitaxial growth. This epitaxial growth is the same as that for forming the first semiconductor layer 14. Here, the top of the second semiconductor layer 18 is flattened by etching or polishing, and the first semiconductor layer 14 and the second semiconductor layer 18 are not formed as shown in FIG. A transparent insulator 22 is formed in the portion. For the formation of the transparent insulator 22, for example, a spin coating method can be used. Finally, a transparent electrode 34 is formed on the second semiconductor layer 18 and the transparent insulator 22 (FIG. 7 (4)). As this electrode, for example, a metal such as Al is used, and it is optional to provide a contact layer (not shown) when depositing the metal.

FIG. 10 shows a group III nitride compound represented by Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0) according to the present invention. FIG. 6 is a diagram showing another method for manufacturing the nitride-based semiconductor light-emitting element 10 made of In FIG. 10, the same reference numerals as those in FIG.

  FIG. 10 shows a step of flattening the upper part of the grown second semiconductor layer 18 and the insulator 22 by etching or polishing after the step of forming the transparent insulator 22. In FIG. 10, after forming the active layer 16 (FIG. 10 (1)), the second semiconductor layer 18 is laminated, and further, a transparent insulator 22 is formed (FIG. 10 (2)). As described with reference to FIG. 7, for the formation of the transparent insulator 22, for example, a spin coating method can be used. Then, the upper surfaces of the second semiconductor layer 18 and the transparent insulator 22 are flattened (FIG. 10 (3)). Thereafter, a transparent electrode layer 34 is formed as shown in FIG.

Here, FIG. 8 and FIG. 9 are referred to as an example of the substrate processing step. FIG. 8 shows a group III nitride-based compound represented by Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0) according to the present invention. FIG. 4 is a diagram showing a substrate processing step in the method for manufacturing a nitride-based semiconductor light-emitting element 10 as described above. FIG. 8 shows a step of performing mask patterning on the substrate 12 (FIG. 8A) and a step of half-etching the substrate (FIG. 8B) as substrate processing steps. Here, the mask patterning mask 42 is used for half-etching the substrate.

FIG. 9 is a group III nitride compound represented by Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0) according to the present invention. FIG. 6 is a diagram showing another method for manufacturing the nitride-based semiconductor light-emitting element 10 made of

  In FIG. 9, as a substrate processing step, a step of forming a buffer layer etching mask 44 for forming the first semiconductor layer 14 on the substrate 12 (FIG. 9A), and a step on the buffer layer 24 are performed. The process (FIG. 9 (2) (3)) which forms a convex part in one part is shown. Here, the buffer layer etching mask 44 is used for half-etching the buffer layer 24, and a convex portion is formed by half-etching the buffer layer 24.

  Returning to FIG. In FIG. 8, the substrate 12 is half-etched with the mask patterning mask 42 (FIG. 8B). After that, if the buffer layer 24 is provided (FIG. 8 (3)) and the first semiconductor layer 14 is formed (FIG. 8 (4)), the first semiconductor layer 14 is partially formed by this substrate processing step. Can be formed.

  Refer to FIG. 9 again. In FIG. 4, a mask layer 14 is provided for the buffer layer 12 (FIG. 9 (2)), the buffer layer 12 is half-etched (FIG. 9 (3)), and then the first semiconductor layer 14 is formed. To do. Since the ELO method is used to form the semiconductor layer 14 and selective lateral growth is performed, the first semiconductor layer 14 grows around the vicinity of the convex portion 13.

  Therefore, as the substrate processing step, the mask layer 26 is formed, the buffer layer 24 is etched, the substrate 12 is etched, or a convex portion is provided on the buffer layer 24, so that the crystal quality is good. The semiconductor element 10 having the semiconductor layer 20 can be formed.

  The nitride semiconductor light emitting device of the present invention can be applied as an LED or LD. Moreover, the method for manufacturing a nitride-based semiconductor light-emitting element according to the present invention can be applied to the manufacture of LEDs and LDs.

It is a figure which shows the nitride type semiconductor light-emitting device which consists of a group III nitride type compound which concerns on this invention. It is a figure which shows the other nitride type semiconductor light-emitting device which consists of a group III nitride type compound which concerns on this invention. It is a figure which shows the other nitride type semiconductor light-emitting device which consists of a group III nitride type compound which concerns on this invention. It is the figure which comprised the nitride-type semiconductor light-emitting device based on this invention as a light emitting diode (LED). It is a figure which shows the state of light emission at the time of using the nitride type semiconductor light-emitting device which consists of a group III nitride type compound which concerns on this invention as a light emitting diode (LED). It is a figure which shows the manufacturing method of the nitride type semiconductor light-emitting device which consists of a group III nitride type compound which concerns on this invention. It is a figure which shows the manufacturing method of the nitride type semiconductor light-emitting device which consists of a group III nitride type compound which concerns on this invention. It is a figure which shows the board | substrate process process in the other manufacturing method of the nitride type semiconductor light-emitting device which consists of a group III nitride type compound concerning this invention. It is a figure which shows the board | substrate process process in the other manufacturing method of the nitride type semiconductor light-emitting device which consists of a group III nitride type compound concerning this invention. It is a figure which shows the other manufacturing method of the nitride type semiconductor light-emitting device which consists of a group III nitride type compound which concerns on this invention. It is a figure which shows what is generally called a "board | substrate." It is a figure which shows the selection lateral direction growth by ELO method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Nitride semiconductor light emitting element 12 Substrate 14 First semiconductor layer 16 Active layer 18 Second semiconductor layer 20 Semiconductor layer 22 Insulator 24 Buffer layer 26 Mask layer 28 Contact part 32 Mask part 34 Electrode layer 42 Mask patterning mask 44 Buffer layer etching mask 46 Buffer layer protrusion 51 Sapphire 52 Buffer layer 53 GaN layer 66 Electrode layer

Claims (13)

Nitride-based semiconductor light-emitting device comprising a group III nitride-based compound represented by Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0) Because
A substrate,
A semiconductor layer formed on the substrate, comprising: a first semiconductor layer; an active layer formed on the first semiconductor layer; and a second semiconductor layer formed on the active layer. Including
A semiconductor layer provided with a recess that divides at least the active layer in a direction perpendicular to the substrate from the upper surface;
A nitride-based semiconductor light-emitting element comprising: a transparent insulator formed in the recess of the semiconductor layer. Between the substrate and the first semiconductor layer,
A buffer layer formed on the substrate;
A mask layer formed on the buffer layer, wherein a contact portion for bringing a part of the surface of the buffer layer into contact with the first semiconductor layer, and contact between the buffer layer and the first semiconductor layer The nitride-based semiconductor light-emitting device according to claim 1, further comprising: a mask layer including a mask portion to prevent.   The nitride-based semiconductor light-emitting element according to claim 2, wherein the contact portion of the mask layer has a substantially hexagonal shape when viewed from a direction perpendicular to the substrate.   The nitride-based semiconductor light-emitting element according to claim 1, further comprising a transparent electrode layer on the semiconductor layer. Nitride-based semiconductor light-emitting device comprising a group III nitride-based compound represented by Al _x Ga _y In _1-xy N (where 1 ≧ x ≧ 0, 1 ≧ y ≧ 0, 1 ≧ x + y ≧ 0) A manufacturing method of
A substrate processing step for performing a process for partially forming a first semiconductor layer on the substrate;
Forming a first semiconductor layer by epitaxial growth on the substrate subjected to the treatment;
Forming an active layer on an upper surface of the first semiconductor layer;
Forming a second semiconductor layer on the active layer by epitaxial growth;
And a step of forming a transparent insulator in a portion where the first semiconductor layer, the active layer, and the second semiconductor layer are not formed. The substrate processing step includes
Forming a buffer layer formed on the substrate between the substrate and the first semiconductor layer;
On the buffer layer, a mask including a contact portion for bringing a part of the surface of the buffer layer into contact with the first semiconductor layer, and a mask portion for preventing contact between the buffer layer and the first semiconductor layer. Forming a layer, and the method for producing a nitride-based semiconductor light-emitting element according to claim 5.   The method for manufacturing a nitride-based semiconductor light-emitting element according to claim 6, wherein the contact portion of the buffer layer has a substantially hexagonal shape when viewed from a direction perpendicular to the substrate. The substrate processing step includes
Performing mask patterning on the substrate;
The method for manufacturing a nitride-based semiconductor light-emitting element according to claim 5, further comprising: half-etching the substrate. The substrate processing step includes
Forming a buffer layer for forming the first semiconductor layer on the substrate;
The method for producing a nitride-based semiconductor light-emitting element according to claim 5, further comprising: forming a protrusion on a part of the buffer layer.   Between the step of forming a second semiconductor layer on the active layer by epitaxial growth and the step of forming a transparent insulator in the concave portion of the semiconductor layer, the second semiconductor layer after growth is etched upward. The method of manufacturing a nitride-based semiconductor light-emitting element according to claim 5, further comprising a step of flattening.   The nitride system according to claim 5, further comprising a step of flattening an upper portion of the grown second semiconductor layer and the insulator by etching after the step of forming the transparent insulator. A method for manufacturing a semiconductor light emitting device.   The method for producing a nitride-based semiconductor light-emitting element according to claim 5, comprising a step of providing a transparent electrode layer on the second semiconductor layer and the transparent insulator. . The nitride-based semiconductor light-emitting element according to claim 11, further comprising a step of providing a transparent electrode layer on the second semiconductor layer and the transparent insulator after the step of planarizing the upper portion. Manufacturing method.

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