JP3962283B2 - Manufacturing method of semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor device such as a short wavelength light emitting diode element or a short wavelength semiconductor laser element.
[0002]
[Prior art]
Group III-V nitride semiconductors (InGaAlN) mainly composed of gallium nitride (GaN) have a wide forbidden band width, and therefore, a visible light emitting diode element or a short wavelength semiconductor laser emitting blue light or green light. In particular, light-emitting diode elements have already been put into practical use in large displays and traffic lights, and white light-emitting diode elements that emit light by exciting fluorescent materials are replaced with current lighting fixtures. Is expected.
[0003]
As for semiconductor laser elements, blue-violet semiconductor laser elements for optical disks with high density and large capacity have already reached sample shipment and small production levels.
[0004]
In the past, nitride semiconductor laser elements have had a large crystal defect density in the nitride semiconductor, and thus it has been difficult to extend the lifetime to withstand practical use. Therefore, in a commonly used metal organic chemical vapor deposition (MOCVD) method, for example, a mask pattern made of silicon oxide is formed on a base layer made of a nitride semiconductor, and the mask pattern formed is used. A selective lateral overgrowth (ELOG) method has been proposed in which regrowth is performed on the exposed region of the substrate. According to this ELOG method, the crystal defect density of the conventional layer is 10% due to lateral growth that is not affected by the crystal structure in the underlayer. ⁹ cm ^-2 10 from level ⁷ cm ^-2 Thus, the lifetime of the nitride semiconductor laser device is greatly improved, and a lifetime of 1000 hours or more is now obtained.
[0005]
In addition to reducing the crystal defect density, the flatness of the mirror surface of the resonator mirror greatly affects the characteristics of the semiconductor laser device. A semiconductor cleaved surface is generally used as the mirror surface. However, nitride semiconductors often use sapphire as the substrate for epitaxial growth, and since sapphire and the nitride semiconductor grown thereon have crystal planes shifted from each other by 30 °, sapphire and nitride are used. The cleavage plane with the semiconductor layer does not match. In addition, since sapphire has a very high hardness, it is difficult to obtain a good cleavage plane. Therefore, a method of manufacturing a resonator by etching a nitride semiconductor layer by dry etching using chlorine gas or the like instead of cleaving has been tried, but it is still difficult to form a good resonator. As a result, the value of the threshold current increases.
[0006]
Nitride semiconductor laser devices that exhibit the most excellent operating characteristics at present are nitrided with a film thickness of 100 μm or more by reducing the crystal defects by the above-mentioned ELOG method and by hydride vapor phase epitaxy (HVPE) method. A physical semiconductor layer is inserted. Subsequently, after forming the laser structure by crystal growth, all or a part of the substrate made of sapphire is removed by polishing, and finally cleaved to form a resonator. By adopting such a manufacturing method, it is possible to form a good resonator without being influenced by the substrate made of sapphire, and as a result, it is possible to realize a long lifetime of the laser element.
[0007]
Thus, when the sapphire substrate is separated from the nitride semiconductor layer or the sapphire substrate is made as thin as possible, a good resonator as a semiconductor laser element can be realized.
[0008]
However, since sapphire and nitride semiconductor generally warp in a convex shape after growth due to the difference in thermal expansion coefficient between each other, polishing the sapphire substrate makes it relatively large in area. And it is difficult to remove uniformly.
[0009]
Therefore, a substrate separation technique called a laser lift-off method has been proposed as a sapphire substrate separation technique. That is, after a nitride semiconductor layer is grown on a sapphire substrate, nitriding is performed by irradiating a laser beam having a short wavelength and a high output, such as a KrF excimer laser beam having a wavelength of 248 nm, from the back surface of the substrate. The sapphire substrate is separated from the physical semiconductor layer. Since this laser beam passes through the sapphire substrate and is absorbed only in the vicinity of the interface between the nitride semiconductor layer and the substrate, the vicinity of the interface of the nitride semiconductor layer is locally heated, and the vicinity of the interface of the nitride semiconductor layer Is decomposed to produce, for example, metallic gallium and nitrogen gas. By removing the metal gallium by heating or wet etching, the sapphire substrate can be separated from the nitride semiconductor layer.
[0010]
Further, in order to improve the characteristics of the semiconductor laser element, a nitride semiconductor layer (device layer) in which a sapphire substrate is separated from a dissimilar substrate made of a material different from sapphire or a metal that can be cleaved. It has also been reported to transfer (transcription, transfer). An example of transferring such a laser element structure onto a copper substrate is described in an academic paper "WSWong et al. Jpn. J. Appl. Phys. Vol. 39 p.L1203 (2000)".
[0011]
By the way, the laser lift-off method has a problem of how to diffuse and release the nitrogen gas generated simultaneously with the metal gallium because the nitride semiconductor layer is thermally decomposed, and has accumulated in the vicinity of the interface with the substrate. There is a problem that the nitride semiconductor layer is blown out or cracks are generated after the laser beam is irradiated by the gas pressure.
[0012]
As a method for solving this problem, Japanese Patent Application Laid-Open No. 2001-176813 describes a manufacturing method for releasing nitrogen gas generated during thermal decomposition. Specifically, a gap (gap) is partially provided between the sapphire substrate and the nitride semiconductor layer using the above-described ELOG method or the like, and the generated nitrogen gas is released from this gap.
[0013]
As described above, according to the so-called ELOG method, the crystal defect density is reduced by re-growing the nitride semiconductor layer in the lateral direction (direction parallel to the substrate surface). Further, when laser lift-off is performed on the nitride semiconductor layer having a gap, the sapphire substrate can be separated from the nitride semiconductor layer without generating cracks.
[0014]
[Problems to be solved by the invention]
However, when the conventional ELOG method described in the above publication is grown to a film thickness of several μm or more necessary for the laser structure, the crystal defects are reduced, and the stress in the semiconductor layer is increased. As a result, cracks occur in the semiconductor layer, making it difficult to increase the film thickness.
[0015]
Further, in the conventional laser lift-off method, in order to release the nitrogen gas generated between the substrate and the semiconductor layer, the nitrogen gas is not sufficiently diffused only from the opening opening on the side surface of the wafer. The gas pressure increases, and a crack is generated in the semiconductor layer after the laser light irradiation.
[0016]
As described above, the ELOG method for reducing crystal defects has a problem in that the film thickness is limited and cracks are likely to occur. In the laser lift-off method, the substrate and the semiconductor layer are separated by the generated nitrogen gas. There is a problem in that the gas pressure at the interface increases and cracks occur in the semiconductor layer.
[0017]
In view of the above-described conventional problems, an object of the present invention is to prevent cracks from occurring in a semiconductor layer grown on a substrate.
[0018]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a method for manufacturing a semiconductor device in which a thermal decomposition layer is formed between a first semiconductor layer selectively formed on a substrate and a substrate, and then a first semiconductor layer is formed. The second semiconductor layer is formed using the semiconductor layer as a seed crystal.
[0019]
Specifically, in the first method for manufacturing a semiconductor device according to the present invention, a first semiconductor layer forming step of selectively forming a first semiconductor layer having a plurality of openings on a first substrate. Irradiation light having energy smaller than the forbidden band width of the first substrate and larger than the forbidden band width of the first semiconductor layer from the surface opposite to the first semiconductor layer with respect to the first substrate. A pyrolysis layer forming step of forming a pyrolysis layer formed by pyrolyzing the first semiconductor layer on at least a part of the first semiconductor layer, and using the first semiconductor layer as a seed crystal And a second semiconductor layer growth step for growing the second semiconductor layer.
[0020]
According to the first method for manufacturing a semiconductor device, a first semiconductor layer having a plurality of openings is selectively formed on a first substrate, and then the at least part of the first semiconductor layer is coated with the first semiconductor layer. A pyrolysis layer is formed by thermally decomposing the first semiconductor layer with irradiation light. Subsequently, a second semiconductor layer is grown using the first semiconductor layer as a seed crystal. Thereby, even when the power density of the irradiation light is sufficiently large and the decomposition gas is generated by the thermal decomposition of the first semiconductor layer, the first semiconductor layer is selectively formed on the substrate. Since the gas easily diffuses, the gas pressure between the first semiconductor layer and the first substrate does not increase, and as a result, no crack is generated in the first semiconductor layer.
[0021]
Furthermore, since the second semiconductor layer is grown using the first semiconductor layer as a seed crystal, the second semiconductor layer is less susceptible to lattice mismatch or a difference in thermal expansion coefficient during growth. The crystal defect density of the semiconductor layer is reduced and the film thickness can be increased. In addition, when the second semiconductor layer is formed so as to promote lateral growth from the first semiconductor layer, the crystal defect density is increased in the portion of the second semiconductor layer above the opening of the first semiconductor layer. This can be further reduced.
[0022]
In the first method for manufacturing a semiconductor device, the first semiconductor layer forming step selectively removes the exposed portion of the first substrate from the first semiconductor layer, thereby forming an exposed portion of the first substrate. It is preferable that the process of forming a groove part is included.
[0023]
In the first method for manufacturing a semiconductor device, the first semiconductor layer forming step includes a step of forming the first semiconductor layer with a plurality of semiconductor layers having different compositions, and in the second semiconductor layer growing step, It is preferable that the second semiconductor layer is grown using a semiconductor layer at a position away from the substrate among the plurality of semiconductor layers in the first semiconductor layer as a seed crystal.
[0024]
A second semiconductor device manufacturing method according to the present invention includes a mask film forming step of selectively forming a mask film having a plurality of openings on a first substrate, and a mask film on the first substrate. A first semiconductor layer growth step of growing a first semiconductor layer on an exposed surface from each opening, and a surface of the first substrate from a surface opposite to the first semiconductor layer with respect to the first substrate; By irradiating irradiation light having energy smaller than the forbidden band width and larger than the forbidden band width of the first semiconductor layer, at least a part of the first semiconductor layer is thermally decomposed. A thermal decomposition layer forming step for forming the thermal decomposition layer, and a second semiconductor layer growth step for growing the second semiconductor layer using the first semiconductor layer as a seed crystal.
[0025]
According to the second method for manufacturing a semiconductor device, a mask film having a plurality of openings is selectively formed on the first substrate, and then exposed from each opening of the mask film on the first substrate. A first semiconductor layer is grown on the surface. Further, a thermal decomposition layer formed by thermally decomposing the first semiconductor layer with irradiation light is formed on at least a part of the first semiconductor layer. Accordingly, as in the first method for manufacturing a semiconductor device, even when the power density of irradiation light is sufficiently large and decomposition gas is generated due to thermal decomposition of the first semiconductor layer, the first semiconductor layer is a substrate. Since the decomposition gas easily diffuses because it is selectively formed on the first semiconductor layer, the gas pressure between the first semiconductor layer and the first substrate does not increase, and as a result, the first semiconductor There are no cracks in the layer.
[0026]
Furthermore, since the second semiconductor layer is grown using the first semiconductor layer as a seed crystal, the second semiconductor layer is less susceptible to lattice mismatch or a difference in thermal expansion coefficient during growth. When the second semiconductor layer is formed so as to promote lateral growth from the first semiconductor layer, the crystal defect density of the semiconductor layer can be reduced and the film thickness can be increased. In the upper part of the opening of one semiconductor layer, the crystal defect density can be further reduced.
[0027]
In the second method for manufacturing a semiconductor device, the first semiconductor layer growth step includes a step of growing the first semiconductor layer on the mask film so that the mask film is partially exposed. The semiconductor device manufacturing method preferably further includes a step of removing the mask film before the thermal decomposition layer forming step.
[0028]
In the second method of manufacturing a semiconductor device, the first semiconductor layer growth step includes a step of growing the first semiconductor layer on the mask film so as to cover the mask film, and a thermal decomposition layer forming step Preferably, the method further includes a step of removing the mask film after partially exposing the upper region of the mask film in the first semiconductor layer.
[0029]
In the second method for manufacturing a semiconductor device, the mask film may be a single layer film made of any one of silicon oxide, silicon nitride, and zinc oxide, or a laminated film including two or more of these. preferable.
[0030]
The method for manufacturing the first or second semiconductor device further includes a substrate separation step of separating the first substrate from the first semiconductor layer and the second semiconductor layer after the second semiconductor layer growth step. It is preferable.
[0031]
In this case, in the substrate separation step, it is preferable that the first substrate is separated by heating the pyrolysis layer or by removing it with an acidic solution.
[0032]
The manufacturing method of the first or second semiconductor device further includes a step of bonding a second substrate made of a material different from the first substrate to the second semiconductor layer before or after the thermal decomposition layer forming step. Preferably it is.
[0033]
In the first or second semiconductor device manufacturing method, the second semiconductor layer preferably includes an active layer. Here, the active layer refers to, for example, a light emitting layer in a light emitting diode element or a semiconductor laser element, or a carrier traveling layer in an electronic device.
[0034]
In the first or second semiconductor device manufacturing method, the first semiconductor layer and the second semiconductor layer are preferably made of a compound semiconductor containing nitrogen.
[0035]
In the first or second method for manufacturing a semiconductor device, the second substrate is preferably made of silicon, gallium arsenide, gallium phosphide, indium phosphide, silicon carbide, or metal.
[0036]
In the first or second semiconductor device manufacturing method, the first substrate is made of sapphire, magnesium oxide, or lithium gallium aluminum oxide (LiGa). _x Al _1-x O ₂ , Where x is 0 ≦ x ≦ 1).
[0037]
In the first or second method for manufacturing a semiconductor device, the irradiation light is preferably laser light that oscillates in a pulse shape.
[0038]
In the first or second semiconductor device manufacturing method, the irradiation light is preferably a bright line of a mercury lamp.
[0039]
In the first or second method for fabricating a semiconductor device, the irradiation light is preferably irradiated so as to scan the in-plane of the first substrate.
[0040]
In the first or second method for manufacturing a semiconductor device, the irradiation light is preferably irradiated while heating the first substrate.
[0041]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings.
[0042]
FIG. 1A to FIG. 1C show cross-sectional structures in the order of steps in the method for manufacturing a semiconductor device according to the first embodiment of the present invention.
[0043]
First, an underlayer forming layer made of gallium nitride (GaN) having a thickness of about 3 μm at a growth temperature of about 1000 ° C. on a substrate (wafer) 10 made of sapphire, for example, by metal organic chemical vapor deposition (MOCVD). To grow. Here, before the base layer forming layer is grown, a buffer layer (not shown) as an initial growth layer made of gallium nitride or aluminum nitride (AlN) having a thickness of about 50 nm is grown at a growth temperature of about 500 ° C. May be. As the crystal growth method, a molecular beam epitaxy (MBE) method or a hydride vapor phase epitaxy (HVPE) method may be used instead of the MOCVD method. Subsequently, a resist film (not shown) having a stripe-like or dot-like pattern is formed on the base layer forming layer by lithography, and boron chloride (BCl, for example) is formed using the formed resist film as a mask. _Three ) Is subjected to dry etching on the underlayer forming layer by a reactive ion etching (RIE) method using an etching gas as shown in FIG. A base layer 11 having a planar stripe or dot pattern having a plurality of openings 11a is formed.
[0044]
Next, as shown in FIG. 1B, excimer laser light from krypton fluoride (KrF) having a wavelength of 248 nm that oscillates in a pulsed manner from the surface opposite to the base layer 11 with respect to the substrate 10. Irradiate to scan. The irradiated laser light is not absorbed by the substrate 10 but is absorbed by the semiconductor layer 11. The local heat generation of the laser spot at this time causes the semiconductor layer 11 to break the bond between atoms at the interface with the substrate 10, and heat containing metal gallium (Ga) between the substrate 10 and the semiconductor layer 11. A decomposition layer 11b is formed. That is, by irradiating the semiconductor layer 11 with laser light, the semiconductor layer 11 grown on the substrate 10 is separated from the substrate 10 by the thermal decomposition layer 11b while the bonds between the atoms are broken with the substrate 10. It will be in the state where it adhered.
[0045]
In the first embodiment, nitrogen generated at the interface with the substrate 10 in the underlayer 11 (N ₂ ) Since gas diffuses in the lateral direction (direction parallel to the substrate surface) from the side of each underlayer 11 facing each opening 11a, the gas pressure at the interface does not increase and cracks occur in the underlayer 11 There is nothing to do. Note that the effect of diffusing (releasing) nitrogen gas is greater as the pattern width is smaller in the case of a stripe pattern, and is greater as the dot diameter is smaller in the case of a dot pattern. Here, the width and interval of each pattern is about 5 μm.
[0046]
The laser light source may be a third harmonic of a YAG (yttrium, aluminum, garnet) laser having a wavelength of 355 nm or a bright line of a mercury lamp having a wavelength of 365 nm, instead of the KrF excimer laser. When a bright line of a mercury lamp is used as the light source, the spot size can be increased although the power of the output light is inferior to that of the laser, so that the laser light irradiation process can be performed in a short time.
[0047]
Further, since the laser light is oscillated in a pulsed manner in the laser light irradiation step, the output power of the laser light can be remarkably increased, so that the thermal decomposition layer 11a can be reliably formed. In addition, since the laser beam is irradiated while scanning the substrate 10 in the plane thereof, even if the substrate 10 has a relatively large diameter, the laser beam is not affected by the beam diameter.
[0048]
In addition, after the base layer forming layer is grown, the substrate 10 is heated at a temperature of about 500 ° C. in order to alleviate the stress caused by the difference in thermal expansion coefficient between the nitride semiconductor and sapphire generated when cooling to room temperature. Good.
[0049]
Next, as shown in FIG. 1C, gallium nitride (GaN) with a thickness of about 5 μm is formed using the patterned underlayer 11 as a seed crystal under growth conditions that promote lateral growth by MOCVD. A semiconductor layer 12 made of is selectively grown. Here, the growth conditions that promote the lateral growth are, for example, conditions in which the group III atoms on the surfaces of the substrate 10 and the underlayer 11 are kept sufficiently long in distance, that is, there are not too many group V atoms, that is, group V sources. Material gas supply conditions that make the V / III ratio, which is the raw material (mole) supply ratio, to the group III source relatively low, or a normal nitride semiconductor growth temperature of 1000 ° C. to 1020 The temperature condition is about 1050 ° C., which is higher than the temperature of ° C.
[0050]
Here, the crystal growth density of the laterally grown portion from the base layer 11 in the semiconductor layer 12 is lower than that of the base layer 11. In addition, even in the portion of the semiconductor layer 12 grown above the base layer 11, the base layer 11 has the pyrolysis layer 11 b containing metal gallium interposed between the base layer 11 and the semiconductor layer 12. In this case, since the semiconductor layer 12 is less susceptible to the lattice mismatch between sapphire and gallium nitride and the difference in thermal expansion coefficient, the semiconductor layer 12 has fewer crystal defects than the base layer 11.
[0051]
The semiconductor layer 12 may be provided with an active layer (active layer) having a pn junction or a pin junction, and in this way, a light emitting device such as a light emitting diode element or a semiconductor laser element having an active layer with excellent crystallinity. Can be realized.
[0052]
Further, since the growth conditions of the semiconductor layer 12 are set so that the lateral growth is dominant, a minute gap is formed between the semiconductor layer 12 and the substrate 10. Therefore, after the growth process of the semiconductor layer 12 shown in FIG. 1C, the substrate 10 is removed from the semiconductor layer 12 by removing the thermal decomposition layer 11b by wet etching using an acidic solution such as hydrochloric acid (HCl). It is also possible to separate them. Note that in the case where a gap is hardly formed between the regrown semiconductor layer 12 and the substrate, the semiconductor layer 12 is irradiated with laser light through the substrate 10, and new heat is applied to the interface of the semiconductor layer 12 with the substrate 10. After forming the decomposition layer, the new thermal decomposition layer and the thermal decomposition layer 11b may be removed by etching.
[0053]
Thus, when the substrate 10 made of insulating sapphire is separated, for example, when applied to a light-emitting diode element or a semiconductor laser element, the p-side and the n-side are arranged so as to face both the upper and lower surfaces of the semiconductor layer 12. Side electrodes can be formed. Accordingly, the chip area can be reduced and the series resistance can be reduced as compared with the case where the p-side electrode and the n-side electrode are formed on the surface opposite to the insulating substrate while leaving the insulating substrate. be able to.
[0054]
As described above, according to the first embodiment, the base layer 11 having the opening 11a is selectively formed on the main surface of the substrate 10 made of sapphire, and further, between the base layer 11 and the substrate 10. A thermal decomposition layer 11b in which the lower portion of the base layer 11 is thermally decomposed by laser light is formed. Thereafter, the semiconductor layer 12 is selectively grown in the lateral direction using the base layer 11 as a seed crystal with the thermal decomposition layer 11b interposed between the substrate 10 and the crystallinity of the semiconductor layer 12 is remarkably improved. . Further, the substrate 10 can be easily and reliably separated from the semiconductor layer 12 only by removing the thermal decomposition layer 11b by wet etching. Accordingly, the chip size and performance of the light emitting device can be reduced.
[0055]
(First modification of the first embodiment)
FIG. 2A and FIG. 2B show a first modification of the first embodiment of the present invention.
[0056]
In the first modification, in order to facilitate the handling (handling) of the semiconductor layer 12, a heterogeneous substrate having conductivity is bonded to the semiconductor layer 12 before the substrate 10 is separated.
[0057]
As shown in FIG. 2A, after the growth process of the semiconductor layer 12 shown in FIG. 1C, a heterogeneous substrate 50 made of, for example, conductive silicon (Si) is placed between the upper surface of the semiconductor layer 12. Are bonded together with a metal film 51 containing gold (Au) and tin (Sn) interposed therebetween, and then heated to several hundred degrees to alloy the heterogeneous substrate 50 and the semiconductor layer 12 at the interface with the metal film 51, respectively. . Here, indium (In) may be used instead of tin. In addition, a thin film made of gold with titanium (Ti) as a base film may be formed in advance on the surface of the heterogeneous substrate 50 facing the semiconductor layer 12 by vapor deposition or the like.
[0058]
Next, as shown in FIG. 2B, the substrate 10 is separated from the semiconductor layer 12 by removing the thermal decomposition layer 11b by wet etching using an acidic solution such as hydrochloric acid.
[0059]
In the first modification, since the semiconductor layer 12 is transferred (transferred) to the conductive different substrate 50, the series resistance and the parasitic capacitance can be reduced, and the performance of the device can be improved. Furthermore, since the semiconductor layer 12 can be easily cleaved when transferred onto the dissimilar substrate 50 that can be cleaved, for example, a laser structure is formed on the semiconductor layer 12 or a new laser structure is formed on the semiconductor layer 12. It is possible to form a good resonator in the laser structure.
[0060]
(Second modification of the first embodiment)
FIGS. 3A and 3B show a second modification of the first embodiment of the present invention.
[0061]
In the second modification, in order to facilitate the handling of the semiconductor layer 12, after separating the substrate 10, a conductive heterogeneous substrate is bonded to the semiconductor layer 12.
[0062]
First, as shown in FIG. 3A, after the growth process of the semiconductor layer 12 shown in FIG. 1C, the thermal decomposition layer 11b is removed by wet etching using an acidic solution such as hydrochloric acid. The substrate 10 is separated from the semiconductor layer 12.
[0063]
Next, as shown in FIG. 3B, a heterogeneous substrate 50 made of, for example, conductive silicon is bonded to the upper surface of the semiconductor layer 12 with a metal film 51 containing gold and tin interposed therebetween, Thereafter, the substrate is heated to several hundred degrees to alloy the opposing portion of the heterogeneous substrate 50 and the semiconductor layer 12. Here, indium may be used instead of tin. In addition, a thin film made of gold with titanium as a base film may be formed in advance on the opposite surface of the heterogeneous substrate 50 to the base layer 11 and the semiconductor layer 12 by vapor deposition or the like.
[0064]
In the second modification, since the semiconductor layer 12 is transferred (transferred) to the conductive different substrate 50, the series resistance and the parasitic capacitance can be reduced, and the performance of the device can be improved. Furthermore, since the semiconductor layer 12 can be easily cleaved when transferred to a different substrate that can be cleaved, for example, when a laser structure is formed in the semiconductor layer 12 or a laser structure is newly formed on the semiconductor layer 12, It is possible to form a good resonator in the laser structure.
[0065]
(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.
[0066]
FIG. 4A to FIG. 4C show cross-sectional structures in the order of steps in the method for manufacturing a semiconductor device according to the second embodiment of the present invention.
[0067]
First, an underlying layer forming layer made of gallium nitride having a thickness of about 3 μm is grown on a substrate (wafer) 10 made of sapphire at a growth temperature of about 1000 ° C., for example, by MOCVD. In this case, a buffer layer (not shown) made of gallium nitride or aluminum nitride having a thickness of about 50 nm may be grown at a growth temperature of about 500 ° C. before the base layer forming layer is grown. Subsequently, a resist mask having a stripe-like or dot-like pattern or a metal mask (not shown) made of nickel (Ni) is formed on the base layer forming layer, and then, for example, chloride is formed using the formed mask. Dry etching is performed on the underlayer forming layer and the upper portion of the substrate 10 by RIE using boron as an etching gas or ion milling. As a result, as shown in FIG. 4A, the base layer 11 having a planar stripe or dot pattern having a plurality of openings 11 a is formed from the base layer forming layer, and at the top of the substrate 10. Grooves 10a are formed in the exposed portions of the foundation layer 11 from the openings 11a. Here, the width and interval of each pattern is about 5 μm.
[0068]
Next, as shown in FIG. 4B, the substrate 10 is irradiated with a KrF excimer laser beam having a wavelength of 248 nm that oscillates in a pulsed manner from the surface opposite to the base layer 11 with respect to the substrate 10. To do. The irradiated laser light is not absorbed by the substrate 10 but is absorbed by the semiconductor layer 11. Therefore, a portion where the laser light is absorbed generates heat locally, and metallic gallium is formed on the interface of the base layer 11 with the substrate 10. The thermal decomposition layer 11b containing is formed.
[0069]
Also in the second embodiment, the nitrogen gas generated at the interface with the substrate 10 in the underlayer 11 during laser light irradiation also diffuses laterally from the side of each pattern constituting the underlayer 11. The gas pressure at the interface does not increase, and the base layer 11 does not crack. Furthermore, in the second embodiment, since the groove 10a is provided in the exposed portion of the substrate 10 from the base layer 11, the nitrogen gas generated during the laser light irradiation is more easily diffused.
[0070]
Further, as a laser light source, a third harmonic of a YAG laser or an emission line of a mercury lamp may be used instead of the KrF excimer laser. In order to relieve the stress due to the difference in the thermal expansion coefficient between the nitride semiconductor and sapphire generated when the base layer forming layer is grown and then cooled to room temperature in the laser light irradiation process, Heating at a temperature of about 500 ° C. is preferable.
[0071]
Next, as shown in FIG. 4C, a semiconductor made of gallium nitride having a thickness of about 5 μm using the patterned underlayer 11 as a seed crystal under growth conditions that promote lateral growth by MOCVD. Layer 12 is selectively grown. In the second embodiment, the peripheral portion of each pattern of the base layer 11 in the upper part of the substrate 10 is dug down to form the groove 10a, so that the gap between the lower surface of the growing semiconductor layer 12 and the main surface of the substrate 10 is increased. The gap is surely and sufficiently formed. Therefore, when the substrate 10 is separated after the growth process of the semiconductor layer 12 shown in FIG. 4C, a gap is formed by the groove 10a between the substrate 10 and the semiconductor layer 12, so that the thermal decomposition layer 11b Etching removal with an acidic solution can be performed more easily and reliably.
[0072]
Furthermore, since the groove portion 10a is provided on the upper portion of the substrate 10, the stress in the semiconductor layer 12 due to lattice mismatch or a difference in thermal expansion coefficient when the semiconductor layer 12 is grown is higher than that in the first embodiment. Therefore, the crystallinity of the semiconductor layer 12 is improved, and the semiconductor layer 12 can be made thicker.
[0073]
As described above, according to the second embodiment, the base layer 11 having the opening 11a is selectively formed on the main surface of the substrate 10 made of sapphire, and the groove 10a is further formed in the exposed portion of the substrate 10. To do. Thereafter, a thermal decomposition layer 11b is formed between the base layer 11 and the substrate 10 in which the lower portion of the base layer 11 is thermally decomposed by laser light. Subsequently, since the semiconductor layer 12 is selectively laterally grown using the base layer 11 as a seed crystal with the thermal decomposition layer 11b interposed between the substrate 10 and the substrate 10, the crystallinity of the semiconductor layer 12 is remarkably improved. To do. Further, the substrate 10 can be easily and reliably separated from the semiconductor layer 12 only by removing the thermal decomposition layer 11b by wet etching. Therefore, when an active layer including a pn junction (pin junction) is formed in the semiconductor layer 12, high performance such as reduction in the chip size of the light emitting device and reduction in series resistance can be achieved.
[0074]
(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.
[0075]
FIG. 5A to FIG. 5C show cross-sectional structures in the order of steps of the method for manufacturing a semiconductor device according to the third embodiment of the present invention.
[0076]
First, a first underlayer made of gallium nitride having a thickness of about 10 nm at a growth temperature of about 1000 ° C. and an aluminum nitride having a thickness of about 1 μm on a substrate (wafer) 10 made of sapphire, for example, by MOCVD. A second base layer and a third base layer made of gallium nitride having a thickness of about 3 μm are sequentially grown to form a base layer forming layer. In this case, a buffer layer (not shown) made of gallium nitride or aluminum nitride having a thickness of about 50 nm may be grown at a growth temperature of about 500 ° C. before the base layer forming layer is grown. Subsequently, a resist mask having a stripe-like or dot-like pattern or a metal mask (not shown) made of nickel is formed on the base layer forming layer, and then, for example, boron chloride is etched using the formed mask. Dry etching is performed on the underlayer forming layer and the upper portion of the substrate 10 by RIE using gas or ion milling. Accordingly, as shown in FIG. 5A, the first base layer 21, the second base layer 22, and the second base layer 22 have a planar stripe or dot pattern having a plurality of openings 24a from the base layer forming layer. A base layer 24 made of the third base layer is formed. Here, the width and interval of each pattern is about 5 μm.
[0077]
Next, as shown in FIG. 5B, the substrate 10 is scanned with the third harmonic light of the YAG laser having a wavelength of 355 nm that oscillates in a pulse shape from the surface opposite to the base layer 24 with respect to the substrate 10. Irradiate as follows. The irradiated laser light is not absorbed by the substrate 10 but is absorbed by the first underlayer 21, so that the portion where the laser light is absorbed locally generates heat, and the interface of the first underlayer 21 with the substrate 10 occurs. A pyrolysis layer 21a containing metal gallium is formed.
[0078]
Also in the third embodiment, the nitrogen gas generated at the interface of the underlayer 24 with the substrate 10 during laser light irradiation also diffuses laterally from the side of the underlayer 24 facing each opening 24a. Therefore, the gas pressure at the interface does not increase and cracks do not occur in the underlayer 24.
In addition, instead of the third harmonic of the YAG laser, a KrF excimer laser or a mercury lamp emission line may be used as the laser light source. In order to relieve the stress due to the difference in the thermal expansion coefficient between the nitride semiconductor and sapphire generated when the base layer forming layer is grown and then cooled to room temperature in the laser light irradiation process, Heating at a temperature of about 500 ° C. is preferable.
[0079]
Next, as shown in FIG. 5C, a semiconductor made of gallium nitride having a thickness of about 5 μm using the patterned underlayer 24 as a seed crystal under growth conditions that promote lateral growth by MOCVD. Layer 12 is selectively grown. In the third embodiment, when the semiconductor layer 12 is grown using the base layer 24 as a seed crystal, the base layer 24 is made of a first base layer 21 made of gallium nitride, a second base layer 22 made of aluminum nitride, and The third underlayer 23 made of gallium nitride is used. For this reason, for example, when the value of the V / III ratio of the raw material in the semiconductor layer 12 is increased, that is, when the gallium source is made larger than the normal V / III ratio, the thickness of the first underlayer made of gallium nitride is increased. Since the second underlayer 22 does not contain gallium in the composition, it grows from the side surface of the third underlayer 23 mainly made of gallium nitride. As a result, a gap 22 a is reliably formed between the lower surface of the semiconductor layer 12 grown from the third underlayer 23 and the main surface of the substrate 10. Therefore, when the substrate 10 is separated after the growth process of the semiconductor layer 12 shown in FIG. 5C, a gap 22a is formed between the substrate 10 and the semiconductor layer 12, so that the thermal decomposition layer 21a Etching removal with an acidic solution can be performed more easily and reliably.
[0080]
As described above, according to the third embodiment, the base layer 24 made of three layers having the opening 24a on the main surface of the substrate 10 made of sapphire and having different compositions between adjacent layers to be stacked. Selectively form. Thereafter, a thermal decomposition layer 21 a is formed between the base layer 24 and the substrate 10 in which the lower portion of the first base layer 21 is thermally decomposed by laser light. Subsequently, the semiconductor layer 12 is selectively grown in the lateral direction using the third base layer 23 above the base layer 24 as a seed crystal with the thermal decomposition layer 21a interposed between the semiconductor layer 12 and the substrate 10. The crystallinity of 12 is remarkably improved. Further, the substrate 10 can be easily and reliably separated from the semiconductor layer 12 only by removing the thermal decomposition layer 21a by wet etching.
[0081]
In addition, since the semiconductor layer 12 is grown so that a gap 22a is formed between the semiconductor layer 12 and the main surface of the substrate 10, compared with the first embodiment, the lattice mismatch or Since the stress in the semiconductor layer 12 due to the difference in thermal expansion coefficient is reduced, the crystallinity of the semiconductor layer 12 is improved, and thereby the semiconductor layer 12 can be made thicker. Therefore, when an active layer including a pn junction (pin junction) is formed in the semiconductor layer 12, high performance such as reduction in the chip size of the light emitting device and reduction in series resistance can be achieved.
[0082]
In the third embodiment, the base layer 24 has a three-layer structure including a first base layer 21 made of gallium nitride, a second base layer 22 made of aluminum nitride, and a third base layer 23 made of gallium nitride. However, instead of this, a two-layer structure of a lower base layer made of aluminum nitride having a thickness of about 1 μm and an upper base layer made of gallium nitride having a thickness of about 3 μm may be used. In this case, for example, the third harmonic light of a YAG laser having a wavelength of 355 nm is not absorbed by the lower base layer made of aluminum nitride, but is absorbed by the upper base layer made of gallium nitride. It will be formed in the lower part of the formation.
[0083]
(Fourth embodiment)
Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.
[0084]
FIG. 6A to FIG. 6D show cross-sectional structures in the order of steps of the semiconductor device manufacturing method according to the fourth embodiment of the present invention.
[0085]
First, as shown in FIG. 6A, silicon oxide (SiO 2) having a film thickness of about 300 nm is formed on a substrate (wafer) 10 made of sapphire by, for example, a vapor deposition method (Chemical Vapor Deposition: CVD). ₂ ) Is formed. Here, as the source gas, for example, monosilane (SiH _Four ) And oxygen (O ₂ ) And the film forming temperature is about 300 ° C. Subsequently, a resist film (not shown) having a stripe-like or dot-like pattern is formed on the mask film forming film by lithography, and the formed resist film is used as a mask to the mask film forming film. For example, by performing wet etching using hydrofluoric acid (HF) as an etching solution, as shown in FIG. 6A, a planar stripe or dot shape having a plurality of openings 60a is formed from the mask film formation film. A mask film 60 having the following pattern is formed. Here, the width and interval of each pattern is about 5 μm.
[0086]
Next, as shown in FIG. 6B, an underlayer 31 made of gallium nitride having a thickness of about 10 nm is formed on each exposed portion from the opening 60a of the mask film 60 in the substrate 10 by, for example, MOCVD. To grow. As described above, in the fourth embodiment, the main surface of the substrate 10 is hardly exposed and is covered with the mask film 60 made of silicon oxide and the base layer 31 made of gallium nitride.
[0087]
Next, as shown in FIG. 6C, the substrate 10 is irradiated with a KrF excimer laser beam having a wavelength of 248 nm oscillated in a pulsed manner from the surface opposite to the base layer 31 with respect to the substrate 10. To do. The irradiated laser light is not absorbed by the substrate 10 but is absorbed by the semiconductor layer 31, so that the portion that absorbed the laser light generates heat locally, and metallic gallium is formed at the interface between the base layer 31 and the substrate 10. The thermal decomposition layer 31a containing is formed. Here, the thickness of the underlayer 31 is set to be smaller than the thickness of the mask film 60 in order to facilitate the diffusion of nitrogen gas generated by the decomposition of the underlayer 31 due to laser light irradiation. . Therefore, it is desirable that gallium nitride is not grown on the mask film 60.
[0088]
The laser light source may be a third harmonic of a YAG laser or an emission line of a mercury lamp instead of the KrF excimer laser. In order to relieve the stress due to the difference in the thermal expansion coefficient between the nitride semiconductor and sapphire generated when the base layer forming layer is grown and then cooled to room temperature in the laser light irradiation process, Heating at a temperature of about 500 ° C. is preferable.
[0089]
Next, as shown in FIG. 6D, gallium nitride having a thickness of about 5 μm is formed by using the underlayer 31 selectively formed as a seed crystal under growth conditions that promote lateral growth by MOCVD. A semiconductor layer 12 made of is selectively grown. In the fourth embodiment, since the semiconductor layer 12 is grown on the upper surface of the mask film 60 under the condition that the lateral growth is promoted, the crystal defect density thereof is lower than that of the base layer 31.
[0090]
Further, even in the portion of the semiconductor layer 12 grown above the base layer 31, the base layer 31 has a pyrolysis layer 31 a containing metallic gallium between the base layer 31 and the semiconductor layer 12. Is not affected by the lattice mismatch between sapphire and gallium nitride and the difference in thermal expansion coefficient. As a result, the crystallinity of the semiconductor layer 12 is greatly improved as compared with the case where the base layer 31 is not provided with the thermal decomposition layer 31a.
[0091]
Subsequently, after the growth process of the semiconductor layer 12 shown in FIG. 6D, the thermal decomposition layer 31a and the mask film 60 are removed by wet etching using a mixed solution of hydrochloric acid and hydrofluoric acid, for example. Thus, the substrate 10 can be separated from the semiconductor layer 12.
[0092]
As described above, according to the fourth embodiment, the mask film 60 that has the opening 60a on the main surface of the substrate 10 made of sapphire and on which the nitride semiconductor does not substantially grow is selectively formed. The base layer 31 made of gallium nitride having a thickness smaller than that of the mask film 60 is grown on the exposed portion of the main surface of the substrate 10 from the mask film 60. Subsequently, a thermal decomposition layer 31 a in which the lower portion of the base layer 312 is thermally decomposed by laser light is formed between the base layer 31 and the substrate 10, and then the thermal decomposition layer 31 a is interposed between the base layer 10 and the substrate 10. In this state, the semiconductor layer 12 is selectively grown in the lateral direction using the base layer 31 as a seed crystal, so that the crystallinity of the semiconductor layer 12 is remarkably improved. Further, the substrate 10 can be easily and reliably separated from the semiconductor layer 12 only by removing the thermal decomposition layer 31a and the mask film 60 by wet etching. Therefore, when an active layer including a pn junction (pin junction) is formed in the semiconductor layer 12, high performance such as reduction in the chip size of the light emitting device and reduction in series resistance can be achieved.
[0093]
(Fifth embodiment)
Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings.
[0094]
FIG. 7A to FIG. 7D show cross-sectional structures in the order of steps in the method for manufacturing a semiconductor device according to the fifth embodiment of the present invention.
[0095]
First, as shown in FIG. 7A, a mask film formation film made of silicon oxide having a thickness of about 300 nm is formed on a substrate (wafer) 10 made of sapphire by, for example, CVD. Subsequently, a resist film (not shown) having a stripe-like or dot-like pattern is formed on the mask film forming film by lithography, and the formed resist film is used as a mask to the mask film forming film. For example, by performing wet etching using hydrofluoric acid as an etching solution, a planar stripe or dot pattern having a plurality of openings 60a is formed from the mask film formation film as shown in FIG. A mask film 60 is formed. Here, it is preferable that the width and interval of each pattern be small, for example, about 1 μm.
[0096]
Next, as shown in FIG. 7B, the underlayer 32 made of gallium nitride having a thickness of about 1 μm is formed on each exposed portion of the substrate 10 from the opening 60a of the mask film 60 by, eg, MOCVD. Grow under conditions where lateral growth becomes dominant. At this time, the underlying layer 32 grown from the openings 60a adjacent to each other grows from both sides of the mask film 60 toward the central portion, but the growth is stopped in a state where the opposing side surfaces of the underlying layer 32 are not in contact with each other. As a result, the central portion of the upper surface of each pattern of the mask film 60 is exposed.
[0097]
Here, the underlayer 32 is crystal-grown so that the central portion of the upper surface of each pattern of the mask film 60 is exposed. Instead, the underlayer 32 is so formed as to cover the mask film on the substrate 10. The substrate is grown almost flat, and then the upper portion of the mask film 60 in the underlying layer 32 is selectively etched by, eg, RIE, thereby exposing the central portion of the upper surface of each pattern of the mask film 60. Also good.
[0098]
Next, as shown in FIG. 7C, the mask film 60 is removed by performing wet etching with, for example, hydrofluoric acid on the substrate 10 on which the underlayer 32 has been selectively grown. As described above, when the mask film 60 is selectively removed, a hook-shaped portion is formed on the side portion of each pattern of the base layer 32, and the main surface of the substrate 10 is exposed between the patterns. Subsequently, the substrate 10 is irradiated with a KrF excimer laser beam having a wavelength of 248 nm oscillated in a pulsed manner from the surface opposite to the base layer 32 so as to scan the substrate 10. The irradiated laser light is not absorbed by the substrate 10 but is absorbed by the semiconductor layer 32, so that the portion that absorbed the laser light generates heat locally, and metallic gallium is formed at the interface between the base layer 32 and the substrate 10. The thermal decomposition layer 32a containing is formed. Here, as in the first to third embodiments, since the side of each pattern in the underlayer 32 is vacant, nitrogen gas generated by thermal decomposition of the underlayer 32 is likely to diffuse. As a result, the semiconductor layer 12 is less likely to crack when irradiated with laser light.
[0099]
The laser light source may be a third harmonic of a YAG laser or an emission line of a mercury lamp instead of the KrF excimer laser. In the laser light irradiation step, the substrate 10 is preferably heated at a temperature of about 500 ° C.
[0100]
Next, as shown in FIG. 7D, gallium nitride having a thickness of about 5 μm is formed by using the underlayer 32 selectively formed as a seed crystal under growth conditions that promote lateral growth by MOCVD. A semiconductor layer 12 made of is selectively grown. In the fifth embodiment, the semiconductor layer 12 grows under the condition that the lateral growth is promoted from the side hook-shaped portion in the underlayer 32, so that its crystal defect density is lower than that of the underlayer 31. .
[0101]
Subsequently, after the step of growing the semiconductor layer 12 shown in FIG. 7D, the substrate 10 can be separated from the semiconductor layer 12 by removing the thermal decomposition layer 32a, for example, by wet etching using hydrochloric acid. It is. At this time, since the gap 32b formed by removing the mask film 60 remains between the substrate 10 and the semiconductor layer 12, the substrate 10 can be easily separated as compared with the first embodiment.
[0102]
As described above, according to the fifth embodiment, the mask film 60 that has the opening 60a on the main surface of the sapphire substrate 10 and on which the nitride semiconductor does not substantially grow is selectively formed. The base layer 32 made of gallium nitride is grown so as to leave the central portion of the mask film 60 on the exposed portion from the mask film 60 on the main surface of the substrate 10. Subsequently, after removing the mask film 60 by etching, a thermal decomposition layer 32a in which the lower portion of the base layer 32 is thermally decomposed by laser light is formed between the base layer 32 and the substrate 10, and then the substrate 10 and Since the semiconductor layer 12 is selectively grown in the lateral direction using the underlayer 32 as a seed crystal with the thermal decomposition layer 32a interposed therebetween, the crystallinity of the semiconductor layer 12 is remarkably improved. Further, the substrate 10 can be easily and reliably separated from the semiconductor layer 12 only by removing the thermal decomposition layer 32a by wet etching. Therefore, when an active layer including a pn junction (pin junction) is formed in the semiconductor layer 12, high performance such as reduction in the chip size of the light emitting device and reduction in series resistance can be achieved.
[0103]
In the fourth or fifth embodiment, the mask film 60 is not limited to silicon oxide, and silicon nitride (Si _Three N _Four ) Or zinc oxide (ZnO) may be used, or a laminated film including two or more of these containing silicon oxide may be used. However, as an etching solution for the mask film 60, for example, an etching solution that can selectively remove the mask film 60 such as hot phosphoric acid or hydrofluoric acid in the case of silicon nitride and aqua regia in the case of zinc oxide. It is necessary to choose.
[0104]
In each of the second to fifth embodiments, as in the first modification example or the second modification example of the first embodiment, silicon is not formed on the semiconductor layer 12 before or after the substrate 10 is separated. A heterogeneous substrate 50 made of, for example, may be bonded.
[0105]
Further, in each of the first to fifth embodiments, the surface orientation of the main surface of the substrate 10 made of sapphire is not particularly limited, and may be a general surface orientation such as (0001) surface, for example. A main surface having a so-called off-angle slightly offset from the (0001) surface may be used.
[0106]
Further, the material of the substrate 10 is not limited to sapphire, for example, magnesium oxide (MgO) or lithium gallium aluminum oxide (LiGa). _x Al _1-x O ₂ , 0 ≦ x ≦ 1) may be used. In this way, a nitride semiconductor having a large forbidden band and excellent crystallinity can be formed, so that high brightness and low operating current can be achieved, and high-performance blue having excellent electrical and optical characteristics. A purple visible light emitting element, that is, a light emitting diode element and a semiconductor laser element can be realized.
[0107]
Further, although silicon (Si) is used for the heterogeneous substrate 50 to which the semiconductor layer 12 is transferred instead of the substrate 10 made of sapphire, it is not limited thereto. That is, the main surface is (100) plane gallium arsenide (GaAs), gallium phosphide (GaP), indium phosphide (InP), silicon carbide (SiC), etc. A semiconductor substrate or a metal substrate such as copper (Cu) may be used. For example, since silicon, silicon carbide, and a metal substrate are excellent in heat dissipation, the life of the element can be extended when applied to a semiconductor laser element. Further, since gallium arsenide, gallium phosphide, and indium phosphide are easily cleaved, a good cleaved surface can also be obtained in the semiconductor layer at the time of cleavage. An end face can be formed. As a result, the threshold current of the laser element can be reduced, so that the performance of the laser element can be improved.
[0108]
The underlayers 11, 24, 31, 32 and the semiconductor layer 12 are not necessarily limited to the MOCVD method, and may be performed by, for example, a molecular beam epitaxy method or a hydride vapor phase growth method. Further, the growth method may be different for each semiconductor layer.
[0109]
In each of the first to fifth embodiments, the semiconductor layer 12 has the general formula In. _x Ga _y Al _1-xy N (where x and y are 0 ≦ x, y ≦ 1, 0 ≦ x + y ≦ 1) may include a pn junction (pin junction) including the light emitting layer. In _x Ga _y Al _1-xy A pn junction (pin junction) including a light emitting layer made of N may be formed by growth.
[0110]
In addition, the buffer layer (initial growth layer) in the underlying layers 11, 24, 31, and 32 is not limited to gallium nitride or aluminum nitride, _u Ga _v Al _1-uv Any nitride semiconductor may be used as long as it is N (where u and v are 0 ≦ u, v ≦ 1, 0 ≦ u + v ≦ 1).
[0111]
【The invention's effect】
According to the method for manufacturing a semiconductor device according to the present invention, the first semiconductor layer is selected on the substrate even when the power density of the irradiation light is sufficiently large and the decomposition gas is generated by the thermal decomposition of the first semiconductor layer. Since the decomposition gas is easily diffused, the gas pressure between the first semiconductor layer and the first substrate does not increase, and as a result, the first semiconductor layer is cracked. Will not occur.
[0112]
Further, the second semiconductor layer is grown using the first semiconductor layer having a thermal decomposition layer interposed between the second semiconductor layer and the substrate as a seed crystal, so that the second semiconductor layer does not have lattice mismatch or thermal expansion during the growth. Since the second semiconductor layer is less affected by the difference in the coefficients, the crystal defect density of the second semiconductor layer is reduced and the film thickness can be increased.
[Brief description of the drawings]
FIGS. 1A to 1C are sectional views of a semiconductor device according to a first embodiment of the present invention, illustrating a method of manufacturing a semiconductor device in order of processes.
FIGS. 2A and 2B are process cross-sectional views illustrating a method of manufacturing a semiconductor device according to a first modification of the first embodiment of the present invention.
FIGS. 3A and 3B are cross-sectional views in order of steps showing a method for manufacturing a semiconductor device according to a second modification of the first embodiment of the present invention. FIGS.
4A to 4C are structural cross-sectional views in order of steps showing a method for manufacturing a semiconductor device according to a second embodiment of the present invention.
FIGS. 5A to 5C are cross-sectional views in order of steps showing a method for manufacturing a semiconductor device according to a third embodiment of the present invention. FIGS.
FIGS. 6A to 6D are structural cross-sectional views in order of steps showing a method for manufacturing a semiconductor device according to a fourth embodiment of the present invention. FIGS.
FIGS. 7A to 7D are structural cross-sectional views in order of steps showing a method for manufacturing a semiconductor device according to a fifth embodiment of the present invention. FIGS.
[Explanation of symbols]
10 Substrate (first substrate)
10a Groove
11 Underlayer (first semiconductor layer)
11a opening
11b Thermal decomposition layer
12 Semiconductor layer (second semiconductor layer)
21 First underlayer
21a Pyrolysis layer
22 Second underlayer
22a gap
23 Third underlayer
24 Underlayer (first semiconductor layer)
24a opening
31 Underlayer (first semiconductor layer)
31a Pyrolysis layer
32 Underlayer (first semiconductor layer)
32a Pyrolysis layer
32b gap
50 Different substrate (second substrate)
51 Metal film
60 Mask film
60a opening

Claims (18)

A first semiconductor layer forming step of selectively forming a first semiconductor layer having a plurality of openings on a first substrate;
An energy smaller than the forbidden band width of the first substrate and larger than the forbidden band width of the first semiconductor layer from a surface opposite to the first semiconductor layer with respect to the first substrate. A thermal decomposition layer forming step of forming a thermal decomposition layer formed by thermal decomposition of the first semiconductor layer on at least a part of the first semiconductor layer by irradiating with irradiation light;
A method of manufacturing a semiconductor device, comprising: a second semiconductor layer growth step of growing a second semiconductor layer using the first semiconductor layer as a seed crystal. The first semiconductor layer forming step includes a step of forming a groove in the exposed portion of the first substrate by selectively removing the exposed portion of the first substrate from the first semiconductor layer. The method of manufacturing a semiconductor device according to claim 1, comprising: The first semiconductor layer forming step includes a step of configuring the first semiconductor layer with a plurality of semiconductor layers having different compositions from each other;
In the second semiconductor layer growth step, the second semiconductor layer is grown using a semiconductor layer at a position away from the substrate among the plurality of semiconductor layers in the first semiconductor layer as a seed crystal. A method for manufacturing a semiconductor device according to claim 1 or 2. A mask film forming step of selectively forming a mask film having a plurality of openings on the first substrate;
A first semiconductor layer growth step of growing a first semiconductor layer on an exposed surface from each opening of the mask film in the first substrate;
An energy smaller than the forbidden band width of the first substrate and larger than the forbidden band width of the first semiconductor layer from a surface opposite to the first semiconductor layer with respect to the first substrate. A thermal decomposition layer forming step of forming a thermal decomposition layer formed by thermal decomposition of the first semiconductor layer on at least a part of the first semiconductor layer by irradiating with irradiation light;
A method of manufacturing a semiconductor device, comprising: a second semiconductor layer growth step of growing a second semiconductor layer using the first semiconductor layer as a seed crystal. The first semiconductor layer growth step includes a step of growing the first semiconductor layer on the mask film so that the mask film is partially exposed;
The method for manufacturing a semiconductor device according to claim 4, further comprising a step of removing the mask film before the thermal decomposition layer forming step. It said first semiconductor layer growing step includes the step of said first semiconductor layer, completely covering not and the upper surface of the mask film on the mask film grows to be flattened,
Prior to the thermal decomposition layer forming step , the mask film is partially removed by selectively removing a region above the mask film in the first semiconductor layer , and then removing the mask film. The method for manufacturing a semiconductor device according to claim 4, further comprising a step. 7. The mask film according to claim 4, wherein the mask film is a single layer film made of any one of silicon oxide, silicon nitride, and zinc oxide, or a laminated film including two or more of these. The manufacturing method of the semiconductor device of any one of them. After the second semiconductor layer growth step,
The semiconductor device according to claim 1, further comprising a substrate separation step of separating the first substrate from the first semiconductor layer and the second semiconductor layer. Manufacturing method. 9. The method of manufacturing a semiconductor device according to claim 8, wherein, in the substrate separation step, the first substrate is separated by heating the thermal decomposition layer or by removing it with an acidic solution. Before or after the pyrolysis layer forming step,
10. The method according to claim 1, further comprising a step of bonding a second substrate made of a material different from that of the first substrate to the second semiconductor layer. A method for manufacturing a semiconductor device. The method for manufacturing a semiconductor device according to claim 1, wherein the second semiconductor layer includes an active layer. The method for manufacturing a semiconductor device according to claim 1, wherein the first semiconductor layer and the second semiconductor layer are made of a compound semiconductor containing nitrogen. 13. The semiconductor device according to claim 10, wherein the second substrate is made of silicon, gallium arsenide, gallium phosphide, indium phosphide, silicon carbide, or metal. Production method. 14. The first substrate is made of sapphire, magnesium oxide, or lithium gallium aluminum oxide (LiGa _x Al _1-x O ₂ , where x is 0 ≦ x ≦ 1). The manufacturing method of the semiconductor device of any one of these. The method of manufacturing a semiconductor device according to claim 1, wherein the irradiation light is laser light that oscillates in a pulse shape. The method of manufacturing a semiconductor device according to claim 1, wherein the irradiation light is an emission line of a mercury lamp. The method of manufacturing a semiconductor device according to claim 1, wherein the irradiation light is irradiated so as to scan an in-plane of the first substrate. The method of manufacturing a semiconductor device according to claim 1, wherein the irradiation light is irradiated while heating the first substrate.

Images