JP3934320B2 - GaN-based semiconductor device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for epitaxial growth of a semiconductor crystal, a method for epitaxially growing a III-V compound semiconductor crystal film on a substrate having different lattice constants and thermal expansion coefficients, and this growth method. About. In particular, it is effective for the application of a GaN-based semiconductor epitaxial growth method in which it is difficult to form a semiconductor film with few crystal defects.
[0002]
Furthermore, the present invention relates to a GaN-based semiconductor element and a method for manufacturing the same, and more particularly to a GaN-based semiconductor element formed on a GaN semiconductor film with few crystal defects and a method for manufacturing the same.
[0003]
[Prior art]
Among group III-V compound semiconductors, gallium nitride (GaN), for example, has attracted attention as a blue light emitting element material because it has a large forbidden band of 3.4 eV and is a direct transition type.
[0004]
As a substrate material for manufacturing a light emitting device using this material, it is desirable to use a bulk crystal of the same substance as the epitaxial layer to be grown. However, in the case of a crystal such as GaN, it is very difficult to produce a bulk crystal due to the high dissociation pressure of nitrogen. Therefore, when manufacturing devices using materials that are very difficult to manufacture bulk crystals, for example, sapphire (Al ₂ O _Three ) Substrates with completely different physical properties and chemical properties such as lattice constant and thermal expansion coefficient, such as substrates, have been used.
[0005]
[Problems to be solved by the invention]
It has been reported that when epitaxial growth is performed on such a hetero-substrate, distortion and defects occur in the substrate and the epitaxial layer, and cracks occur especially when a thick film is grown. Applied Physics Vol. 32 (1993) pp. 1528-1533 ”(Jpn. J. Appl. Phys. Vol 32 (1993) pp. 1528-1533). In such a case, not only the performance as a device is extremely deteriorated, but also the growth layer is often destroyed.
[0006]
In addition, in the lattice-mismatched epitaxial growth, in order to obtain a high-quality epitaxial growth layer having a low dislocation density, the first crystal growth of 1 μm SiO ₂ Japanese Patent Laid-Open No. 8-64791 discloses that a GaN film is selectively grown on a sapphire substrate in which stripes are formed by a film to concentrate lattice defects and dislocations in a specific region. However, in the example of JP-A-8-64791, SiO ₂ Since no growth occurs in the film portion, a flat growth layer cannot be obtained on the entire surface, and the element formation location is restricted.
[0007]
The object of the present invention is that even if epitaxial growth is performed using a hetero-substrate having a different lattice constant or thermal expansion coefficient, distortion and defects are not generated in the substrate or the epitaxial growth layer, and cracks are generated even if a thick film is grown. The object is to provide a growth method for obtaining a difficult epitaxial growth layer.
[0008]
Still another object of the present invention is to provide a GaN-based semiconductor film having few crystal defects by utilizing the above-mentioned epitaxial growth for the growth of a GaN-based semiconductor.
[0009]
Another object of the present invention is to produce a GaN-based semiconductor device structure (for example, a GaN-based semiconductor light-emitting device structure) on the GaN-based semiconductor film formed by the above epitaxial growth, thereby obtaining excellent device characteristics. The object is to provide a semiconductor device (for example, a GaN-based semiconductor light-emitting device).
[0010]
[Means for solving the problems]
The method for forming a GaN-based semiconductor multilayer structure according to the present invention includes a substrate surface having a lattice constant and a thermal expansion coefficient different from those of a GaN-based semiconductor, or a growth region formed by a mask material patterned on the surface of a GaN-based semiconductor formed on the substrate. And forming the GaN-based semiconductor so as to form a facet structure in the growth region. And bending dislocations A step of covering the mask material together with a GaN-based semiconductor in an adjacent growth region and flattening the surface; and a step of forming a stacked structure of GaN-based semiconductor elements on the GaN-based semiconductor film.
[0011]
Also, the method for forming a GaN-based semiconductor multilayer structure according to the present invention grows with a mask material patterned on a substrate surface having a lattice constant or thermal expansion coefficient different from that of a GaN-based semiconductor, or on a GaN-based semiconductor surface formed on the substrate. Forming a region, and growing a GaN-based semiconductor to form a facet structure in the growth region. And bending dislocations A step of covering the mask material together with a GaN-based semiconductor in an adjacent growth region, planarizing a surface, a step of removing at least the substrate and the mask material from the GaN-based semiconductor film, and a GaN-based layer on the GaN-based semiconductor film And a step of forming a stacked structure of semiconductor elements. Alternatively, a step of forming a growth region with a mask material patterned on a substrate surface having a lattice constant or a thermal expansion coefficient different from that of a GaN-based semiconductor or a GaN-based semiconductor surface formed on the substrate, and a GaN-based semiconductor in the growth region Growing semiconductors to form faceted structures And bending dislocations A step of covering the mask material together with a GaN-based semiconductor in an adjacent growth region, planarizing a surface, a step of forming a laminated structure of GaN-based semiconductor elements on the GaN-based semiconductor film, and at least from the GaN-based semiconductor film And a step of removing the substrate and the mask material.
[0012]
Furthermore, the method for forming a GaN-based semiconductor multilayer structure according to the present invention is characterized in that the GaN-based semiconductor element is a GaN-based semiconductor light-emitting element including a double heterostructure. The GaN-based light emitting device is a GaN-based semiconductor laser.
[0013]
The GaN-based semiconductor multilayer structure of the present invention is patterned to form a growth region on a substrate having a lattice constant or thermal expansion coefficient different from that of the GaN-based semiconductor, and on the substrate surface or the GaN-based semiconductor surface formed on the substrate. Growing while forming a facet structure in the growth area with the mask material Bending dislocations, The GaN-based semiconductor film covers the mask material along with the growth of the GaN-based semiconductor in the adjacent growth region, and the planarized GaN-based semiconductor film is embedded and planarized by the growth of the GaN-based semiconductor. A laminated structure of GaN-based semiconductor elements is formed on the GaN-based semiconductor film. Furthermore, at least the substrate and mask material are removed from the GaN-based semiconductor multilayer structure.
[0014]
In the GaN-based semiconductor multilayer structure according to the present invention, the GaN-based semiconductor element is a GaN-based semiconductor light-emitting element including a double heterostructure. Furthermore, the GaN-based light emitting device is a GaN-based semiconductor laser.
[0015]
The method for manufacturing a GaN-based semiconductor device according to the present invention forms a growth region by using a mask material patterned on a substrate surface having a lattice constant or thermal expansion coefficient different from that of a GaN-based semiconductor, or on a GaN-based semiconductor surface formed on the substrate. And growing the GaN-based semiconductor so as to form a facet structure in the growth region. And bending dislocations And a step of covering the mask material together with a GaN-based semiconductor in an adjacent growth region and planarizing the surface, and a step of forming a GaN-based semiconductor element on the planarized GaN-based semiconductor film.
[0016]
In addition, the method for manufacturing a GaN-based semiconductor device according to the present invention provides a growth region using a mask material patterned on a substrate surface having a lattice constant or a thermal expansion coefficient different from that of a GaN-based semiconductor, or a GaN-based semiconductor surface formed on the substrate. And forming a GaN-based semiconductor in the growth region so as to form a facet structure. And bending dislocations A step of covering the mask material together with a GaN-based semiconductor in an adjacent growth region, planarizing a surface, a step of removing at least the substrate and the mask material from the GaN-based semiconductor film, and the planarized GaN-based semiconductor film It has the process of forming a GaN-type semiconductor element on it. Alternatively, a step of forming a growth region with a mask material patterned on a substrate surface having a lattice constant or a thermal expansion coefficient different from that of a GaN-based semiconductor or a GaN-based semiconductor surface formed on the substrate, and a GaN-based semiconductor in the growth region Growing semiconductors to form faceted structures And bending dislocations A step of covering the mask material together with a GaN-based semiconductor in an adjacent growth region, planarizing a surface, forming a GaN-based semiconductor element on the planarized GaN-based semiconductor film, and from the GaN-based semiconductor film And a step of removing at least the substrate and the mask material.
[0017]
Furthermore, the GaN-based semiconductor device manufacturing method of the present invention is characterized in that the GaN-based semiconductor device is a GaN-based semiconductor light-emitting device including a double heterostructure. The GaN-based light emitting device is a GaN-based semiconductor laser.
[0018]
The GaN-based semiconductor device according to the present invention includes a substrate having a lattice constant or a thermal expansion coefficient different from that of a GaN-based semiconductor, and a patterned mask that forms a growth region on the substrate surface or a GaN-based semiconductor surface formed on the substrate. Growing with material and faceted structure in the growth region Bending dislocations, The GaN-based semiconductor film covers the mask material along with the growth of the GaN-based semiconductor in the adjacent growth region, and the planarized GaN-based semiconductor film is embedded and planarized by the growth of the GaN-based semiconductor. A GaN-based semiconductor element is formed on the GaN-based semiconductor film. Further, at least the substrate and the mask material are removed from the GaN-based semiconductor element.
[0019]
Furthermore, the GaN-based semiconductor element is a GaN-based semiconductor light-emitting element including a double hetero structure. The GaN-based light emitting device is a GaN-based semiconductor laser.
[0020]
In the GaN-based semiconductor multilayer structure and the method for forming the same according to the present invention, the GaN-based semiconductor light-emitting element has an undoped quantum well active layer.
[0021]
In the GaN-based semiconductor device and the manufacturing method thereof according to the present invention, the GaN-based semiconductor light-emitting device has an undoped quantum well active layer.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0023]
(First embodiment)
A first embodiment of the present invention will be described with reference to FIG. 1 by taking epitaxial growth of a group III-V compound semiconductor as an example.
[0024]
First, a group III-V compound semiconductor 12 having a property different from that of the substrate material and being the same as the material grown in the next process or having a property similar to that material in lattice constant and thermal expansion coefficient is formed on the substrate. A mask 14 for limiting the growth region on the substrate is formed on the surface by photolithography and wet etching. The shape of the mask was a stripe. At this time, the thickness of the mask 14 was about 10 nm to 2 μm, and the stripe width of the growth region 13 and the mask 14 was usually about 0.1 μm to 10 μm. (FIG. 1 (a)).
[0025]
Next, the III-V group compound semiconductor film is epitaxially grown on the growth region. The substrate with the mask 14 is inserted into the reaction tube of the epitaxial apparatus, and the substrate 11 is heated to a predetermined growth temperature while supplying hydrogen gas, nitrogen gas, or a mixed gas of hydrogen and nitrogen and a group V source gas. To do. After the temperature is stabilized, a group III material is supplied to grow a group III-V compound semiconductor 15 in the growth region 13. The crystal growth method is preferably vapor phase epitaxy (VPE: Vapor Phase Epitaxy) using chloride as a group III material, but organometallic compound vapor phase growth (MOCVD) using an organic metal as a group III material. : Metal Organic Vapor Phase Epitaxy) may be used.
[0026]
The III-V compound semiconductor 15 does not grow on the mask 14 in the initial stage, but crystal growth occurs only in the growth region 13, and a facet structure is formed in the III-V compound semiconductor 15 on the growth region. The growth conditions of the III-V compound semiconductor 15 at this time are the growth temperature of 650 ° C. to 1100 ° C. so that the facet structure is formed, and the Group V raw material supplying the same amount to 200,000 times the supply amount of the Group III raw material. Perform within the supply range. (FIG. 1 (b)).
[0027]
If the epitaxial growth is further continued, the group III-V compound semiconductor 15 grows in a direction perpendicular to the facet structure plane, and thus covers not only the growth region but also the mask 14. And it contacts with the facet structure of the III-V group compound semiconductor 15 of an adjacent growth region (Drawing 1 (c)).
[0028]
When the epitaxial growth is further continued, the facet structure is embedded (FIG. 1D), and finally a III-V group compound semiconductor film 15 having a flat surface can be obtained (FIG. 1E).
[0029]
Normally, when crystal growth of a III-V group compound semiconductor having a different lattice constant or thermal expansion coefficient is performed on a substrate, dislocations due to crystal defects generated at the interface with the substrate extend in a direction perpendicular to the interface. Even if the epitaxial film is thickened, no reduction in dislocation is observed.
[0030]
In the method according to the present embodiment, the facet structure is formed in the growth region by selective growth. This facet appears because the growth rate is slower than the other aspects. Due to the appearance of the facet, the dislocation advances toward the facet, and the dislocation extending perpendicular to the substrate cannot extend in the vertical direction. It was found that crystal defects were bent laterally with facet growth, and as the thickness of the epitaxial film increased, crystal defects decreased in the growth region and appeared at the edge of the crystal or formed a closed loop. . Thereby, reduction of defects in the epitaxial film is measured. By forming and growing the facet structure in this way, crystal defects can be greatly reduced.
[0031]
In particular, in the vapor phase growth by the chloride transport method using chloride as a group III material, the growth of the group III-V compound semiconductor 15 is fast, so that the same surface as the substrate surface of the facet structure disappears quickly. Accordingly, dislocations extending perpendicularly to the substrate will soon extend in a direction different from the substrate surface in the facet structure, and dislocations extending perpendicularly in the III-V compound semiconductor 15 can be greatly reduced.
[0032]
In addition, the organometallic compound vapor phase growth using an organic metal as the group III material has a slower growth rate than the vapor phase growth by the chloride transport method, but the facet structure of the group III-V compound semiconductor 15 as described above. Of these, the same surface as the substrate surface should disappear quickly. For example, if the area of the mask with respect to the growth region is increased, the supply amount of the growth species from the mask increases, so that the growth of the III-V group compound semiconductor 15 in the growth region can be stopped.
[0033]
(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG. 5 by taking epitaxial growth of a III-V group compound semiconductor as an example.
[0034]
Since FIGS. 5A to 5B are manufactured in the same steps as FIGS. 1A to 1E of the first embodiment, the description thereof is omitted. In the second embodiment, after the III-V group compound semiconductor is epitaxially grown and the growth layer is planarized, a second mask is provided (FIG. 5C), and facets are formed as in the first embodiment. A structure is formed and planarization is performed (FIG. 5D).
[0035]
In the second embodiment, the defect density of the group III-V compound semiconductor film formed by repeating the manufacturing steps of FIGS. 1A to 1E can be further reduced.
[0036]
The first embodiment or the second embodiment is effective for crystal growth of a material having a lattice constant or thermal expansion coefficient different from that of the substrate. ₂ O _Three , Si, SiC, MgAl ₂ O _Four , LiGaO ₂ , ZnO, etc., and can be applied to the growth of III-V group compound semiconductors such as GaN, GaAlN, InGaN, InN.
[0037]
In FIG. 1 or FIG. 5, an example is shown in which a mask is formed on the surface of a group III-V compound semiconductor film having the same property as that of the material grown in the next step on the substrate or similar to the material and the lattice constant and thermal expansion coefficient. However, the same effect can be obtained by forming a mask directly on the surface of the substrate 11 and performing the processes of FIGS. 1B to 1E or 5B to 5D.
[0038]
Further, in the present embodiment, the growth region using a stripe pattern as the mask 14 has been described. However, the present invention is not limited to this, and if the facet structure appears, the growth region has a rectangular shape, The mask may be round or triangular.
[0039]
(Third embodiment)
Next, a third embodiment of the present invention will be described. In the third embodiment, the GaN-based semiconductor film is formed by using the epitaxial growth of the III-V group compound semiconductor described in the first embodiment or the second embodiment for the growth of the GaN-based semiconductor. is there.
[0040]
In the third embodiment, the epitaxial growth described in the first embodiment or the second embodiment is used for a GaN-based semiconductor, and the description of the common parts is simplified.
[0041]
First, a mask for limiting a growth region on a substrate is formed on a substrate material having a thermal expansion coefficient and a lattice constant different from those of a GaN-based semiconductor by using a photolithography method and a wet etching method.
[0042]
Next, epitaxial growth of a GaN-based semiconductor is performed on the growth region. A crystal growth method for a GaN-based semiconductor grown in a growth region is based on gallium chloride (GaCl), which is a reaction product of gallium (Ga) and hydrogen chloride (HCl), as a group III material, and ammonia (NH) as a group V material. _Three ) Vapor Phase Epitaxy (VPE), a vapor transport method using a chloride transport method using gas, and Metalorganic Vapor Phase Epitaxy (MOCVD) using an organic metal as a Ga raw material . The growth temperature is 650 ° C. to 1100 ° C., and the supply amount of the group V raw material may be from 1 to 200,000 times the supply amount of the group III raw material.
[0043]
In the epitaxial growth of the GaN-based semiconductor layer, as in the first embodiment, the GaN-based semiconductor does not grow on the mask in the initial stage and crystal growth occurs only in the growth region. A facet structure having a plane orientation different from the plane orientation of the substrate is formed.
[0044]
If the epitaxial growth is continued, the GaN-based semiconductor grows in a direction perpendicular to the facet structure surface, and thus covers not only the growth region but also the mask. And it contacts the facet structure of the GaN-based semiconductor in the adjacent growth region. When the epitaxial growth is further continued, the facet structure is embedded by the GaN-based semiconductor, and finally, a GaN-based semiconductor film having a flat surface can be obtained.
[0045]
Since GaN is difficult to produce bulk crystals, sapphire substrates, SiC substrates, etc. have been used as substrates in conventional GaN-based semiconductor crystal growth, but these substrates have lattice constants and thermal expansion coefficients that are different from those of GaN-based semiconductors. Is different. For this reason, when epitaxial growth of a GaN-based semiconductor is performed, dislocations accompanying crystal defects generated at the interface with the substrate extend in a direction perpendicular to the interface, and even if the epitaxial film is thickened, no reduction in dislocation was observed.
[0046]
In the epitaxial growth method according to the present embodiment, a facet structure having a plane orientation different from the substrate plane orientation is formed in a growth region selectively formed by a mask material on a substrate material having a thermal expansion coefficient or lattice constant different from that of a GaN-based semiconductor. A GaN-based semiconductor is epitaxially grown. This facet appears because the growth rate is slower than the other planes, and with the appearance of the facet, dislocations generated from the vicinity of the interface between the substrate and the GaN-based semiconductor proceed toward the facet, and the dislocations extended perpendicular to the substrate. Cannot extend in the vertical direction.
[0047]
Therefore, the crystal defects of the GaN-based semiconductor are bent in the lateral direction as the facet grows, and as the film thickness increases due to the epitaxial growth of the GaN-based semiconductor, the crystal defects decrease in the growth region and appear at the end of the crystal. Form a closed loop. Thereby, reduction of defects in the epitaxial film is measured.
[0048]
As described above, by growing a GaN-based semiconductor film having a facet structure in a growth region selectively formed on a substrate by a mask, crystal defects in the GaN-based semiconductor film can be greatly reduced.
[0049]
Furthermore, after the GaN-based semiconductor film obtained in the third embodiment is grown to a desired thickness, the substrate (such as a sapphire substrate), the mask, and a part of the GaN-based semiconductor are removed. It can be used as a substrate for a GaN-based semiconductor film with few defects. By producing a GaN-based semiconductor element on such a GaN-based semiconductor film, the crystallinity of the laminated structure of the GaN-based semiconductor element can be improved.
[0050]
When the GaN-based semiconductor light-emitting element is a GaN-based semiconductor light-emitting element, it is possible to form an electrode on the back surface of the substrate in the GaN-based semiconductor light-emitting element that has been a problem with sapphire substrates and the like.
[0051]
Further, when the GaN-based semiconductor light-emitting device is a GaN-based semiconductor laser, it is possible to produce a resonator mirror by cleavage even if a laser structure is formed on a hetero substrate having a cleavage plane different from that of the GaN-based semiconductor.
[0052]
The formation of the GaN-based semiconductor film in the third embodiment has been described using the epitaxial growth of the first embodiment for the sake of explanation, but it can also be applied to the second embodiment.
[0053]
In the description of the third embodiment, an example in which a mask is directly formed on a substrate surface having a lattice constant or a thermal expansion coefficient different from that of a GaN-based semiconductor has been described. A similar effect can be obtained even if a mask is formed on the semiconductor surface.
[0054]
Furthermore, as the mask used in this embodiment, the same material, size, and shape as those in the first embodiment or the second embodiment can be applied. In addition, as the GaN-based semiconductor film in the present embodiment, GaN, AlGaN, InGaN and the like can be mentioned, but GaN is most preferable.
[0055]
Further, as a GaN-based semiconductor element, in addition to a GaN-based semiconductor light-emitting element such as a GaN-based semiconductor laser and a GaN-based LED, it can be applied to devices such as FETs and HBTs.
[0056]
(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIG.
[0057]
In the fourth embodiment, a GaN-based semiconductor thick film is grown on a substrate having a thermal expansion coefficient and a lattice constant different from those of the GaN-based semiconductor by using the epitaxial growth of the first embodiment. A GaN-based semiconductor element is produced on a thick film.
[0058]
In the fourth embodiment, a case where a GaN-based semiconductor light-emitting element is used as a GaN-based semiconductor element on a GaN-based semiconductor film will be described.
[0059]
First, a mask is formed on the substrate surface, and the mask and the growth region are separated by photolithography and wet etching. As the substrate, a substrate in which a GaN-based semiconductor is formed on a substrate material having a thermal expansion coefficient or a lattice constant different from that of the GaN-based semiconductor is used.
[0060]
The shape of the mask and the growth region is a shape in which facets appear in the GaN-based semiconductor in the growth region as described in the first embodiment.
[0061]
Next, epitaxial growth of a GaN-based semiconductor is performed on the growth region. The growth method of a GaN-based semiconductor is based on gallium chloride (GaCl), which is a reaction product of gallium (Ga) and hydrogen chloride (HCl), as a group III source and ammonia (NH) as a group V source. _Three ) A hydride VPE method using a gas is preferable, but a metal organic chemical vapor deposition method (MOVPE) may be used.
[0062]
In the epitaxial growth of the GaN-based semiconductor, as in the first embodiment, the GaN-based semiconductor does not grow on the mask in the initial stage, and crystal growth occurs only in the growth region. A facet structure having a plane orientation different from the plane orientation is formed.
[0063]
If the epitaxial growth is continued, the GaN-based semiconductor grows in a direction perpendicular to the facet structure surface, and thus covers not only the growth region but also the mask. Then, it contacts the facet structure of the GaN-based semiconductor film in the adjacent growth region. When the epitaxial growth is further continued, the facet structure is embedded by the GaN-based semiconductor, and finally, a GaN-based semiconductor film having a flat surface can be obtained.
[0064]
Next, an element structure of a GaN-based semiconductor light-emitting element is fabricated on the GaN-based semiconductor film. After forming the GaN-based semiconductor film, the substrate on which the GaN-based semiconductor film has been formed is set in an MOCVD apparatus, and the n-type GaN layer, the n-type AlGaN clat layer, n at a predetermined temperature, gas flow rate, and V / III ratio. -Type GaN light guide layer, multi-quantum well structure active layer comprising undoped InGaN quantum well layer and undoped InGaN barrier layer, p-type AlGaN layer, p-type GaN light guide layer, p-type AlGaN cladding layer, p-type GaN contact layer in order Form a laser structure.
[0065]
Next, the substrate on which the laser structure is formed is set in a polishing machine, and the substrate, SiO ₂ The mask and a part of the GaN-based semiconductor film are polished to expose the GaN-based semiconductor film. An n-type electrode is formed on the exposed surface of the GaN-based semiconductor film, that is, the back surface side of the GaN-based semiconductor light-emitting element, and a p-type electrode is formed on the front surface side.
[0066]
The following effects are obtained by the fourth embodiment.
[0067]
By growing a GaN-based semiconductor device structure on the GaN-based semiconductor film obtained by the epitaxial growth of the first embodiment, the epitaxial growth in the GaN-based semiconductor device structure that has been a problem in the growth using the conventional sapphire substrate The crystallinity of the film can be improved, and the characteristics of the GaN-based semiconductor element can be improved.
[0068]
Furthermore, when the GaN-based semiconductor device is a GaN-based semiconductor light-emitting device, an electrode can be formed on the back surface, so that the electrode is formed on the surface of the GaN-based semiconductor film by a complicated manufacturing process such as dry etching as in the prior art. The device can be manufactured without any problems, and the electrode manufacturing process can be simplified.
[0069]
When the GaN-based semiconductor light-emitting device is a GaN-based semiconductor laser, the substrate mirror and the mask are removed after the GaN-based semiconductor thick film with few crystal defects is formed. Can be formed. For this reason, compared with the conventional method in which the resonator mirror surface is formed by a complicated process such as dry etching, the yield can be greatly improved.
[0070]
Note that the fourth embodiment is not limited to the above description, and other configurations and growth methods can be adopted as necessary.
[0071]
For example, not only the first embodiment but also the second embodiment can be applied to the epitaxial growth of a GaN-based semiconductor film.
[0072]
Furthermore, the substrate and the mask were removed after the laminated structure of the GaN-based semiconductor element was formed on the GaN-based semiconductor film, but after the formation of the GaN-based semiconductor film, the substrate, the mask, and a part of the GaN-based semiconductor film were removed, and then the GaN-based semiconductor A stacked structure of elements may be manufactured.
[0073]
The example in which the substrate and the mask are removed from the GaN-based semiconductor film has been described. However, if only the crystallinity effect of the GaN-based semiconductor element formed on the GaN-based semiconductor film is desired, the substrate and the mask are removed. Instead of this, an electrode may be formed on the surface side of the GaN-based semiconductor element.
[0074]
Furthermore, as the mask used in this embodiment, the same material, size, and shape as those in the first embodiment or the second embodiment can be applied. In addition, as the GaN-based semiconductor film in the present embodiment, GaN, AlGaN, InGaN and the like can be mentioned, but GaN is most preferable.
[0075]
Further, as a GaN-based semiconductor element, in addition to a GaN-based semiconductor light-emitting element such as a GaN-based semiconductor laser and a GaN-based LED, it can be applied to devices such as FETs and HBTs.
[0076]
【Example】
Next, embodiments of the present invention will be described with reference to the drawings.
[0077]
(First embodiment)
An embodiment of the present invention will be described with reference to FIG. In this embodiment, the substrate is a (0001) plane sapphire (Al ₂ O _Three 1) A substrate in which a GaN film 12 having a thickness of about 1 μm was previously formed on the substrate 11 was used. On the surface of the GaN film 12, SiO ₂ A film was formed and separated into a mask 14 and a growth region 13 by photolithography and wet etching. The growth region 13 and the mask 14 are stripes having a width of 5 μm and 2 μm, respectively. The stripe direction was the <11-20> direction ((FIG. 1A)).
[0078]
The GaN film 15 grown in the growth region 13 is composed of gallium chloride (GaCl), which is a reaction product of gallium (Ga) and hydrogen chloride (HCl), as a group III material, and ammonia (NH) as a group V material. _Three ) A hydride VPE method using gas was used. The substrate 11 is set in a hydride growth apparatus and heated to a growth temperature of 1000 ° C. in a hydrogen atmosphere. After the growth temperature is stabilized, the HCl flow rate is supplied at 20 cc / min, NH _Three A facet structure made of the {1-101} plane of the GaN film 15 was grown in the growth region 13 by supplying the flow rate of 1000 cc / min for about 5 minutes (FIG. 1B). Further, the epitaxial growth was continued for about 20 minutes, and the facet structure 16 was developed until the mask 14 was covered (FIG. 1C).
[0079]
By continuing the epitaxial growth, the facet structure was embedded (FIG. 1D), and finally a GaN film having a flat surface of about 200 μm was formed by the growth for 5 hours (FIG. 1E). After the GaN film 15 was formed, it was cooled to room temperature while supplying ammonia gas and taken out from the growth apparatus.
[0080]
In the first embodiment, crystal growth is performed by forming facets whose side walls are {1-101} planes by selective growth that limits the growth region. This facet appears because the growth rate is slower than the other aspects. Before the facets appear, dislocations that extend perpendicular to the substrate cannot extend in this direction due to the appearance of the facets.
[0081]
Examining the crystal grown according to the present invention in detail, it was found that the facet was bent in the lateral direction with the appearance of the facet, and emerged at the end of the crystal as the thickness of the epitaxial film increased. Thereby, reduction of defects in the epitaxial film is measured.
[0082]
It was confirmed that the GaN film 15 formed according to the first example was free of cracks despite the difference in lattice constant and thermal expansion coefficient from the sapphire substrate 11. Moreover, the GaN film on which the thick film is grown has very few defects, and the defect density is 10 ⁶ cm ² It was about.
[0083]
The GaN film grown in this example has very few defects, and device characteristics can be improved by growing high-quality device structures such as lasers, FETs, and HBTs thereon.
[0084]
Furthermore, the GaN film 15 can be used as a substrate material by removing the sapphire substrate 11 by polishing or the like.
[0085]
In the first embodiment, a hydride VPE method is used for epitaxial growth of a GaN film, but the same effect can be obtained by using a metal organic compound vapor deposition method (MOCVD). Also Al ₂ O _Three Substrate 11 was used, but Si substrate, ZnO substrate, SiC substrate, LiGaO ₂ Substrate, MgAl ₂ O _Four Even if a substrate or the like is used, the same effect can be obtained. Furthermore Al ₂ O _Three Although the GaN film 12 is formed in advance on the substrate 11, a mask may be formed directly on the substrate 11.
[0086]
Further, as the mask 14, SiO ₂ However, the present invention is not limited to this. SiN _x An insulator film such as In this embodiment, the width of the mask 14 is set to 2 μm, but the same effect can be obtained as long as the mask can be embedded. Further, the stripes are formed in the <11-20> direction, but if facets are formed, the direction may be perpendicular to the direction <1-100>, and even at an angle inclined from these directions, it depends on the crystal growth conditions. A facet structure can be formed in the growth region. The crystal growth conditions for forming the facet structure vary depending on the material.
[0087]
Moreover, although the GaN epitaxial growth has been described, the same effect can be obtained by epitaxially growing an InGaN film, an AlGaN film, or an InN film. Further, the same effect can be obtained by adding impurities to the growing III-V group compound.
[0088]
(Second embodiment)
A second embodiment of the present invention will be described with reference to FIG. 1, as in the first embodiment.
[0089]
In the second embodiment, an Al film having a thickness of about 1 μm on a (0001) plane SiC substrate 11 is used as a substrate. _0.1 Ga _0.9 A crystal in which the N film 12 was previously formed was used. This Al _0.1 Ga _0.9 SiO on the surface of the N film 12 ₂ A film was formed and separated into a mask 14 and a growth region 13 by photolithography and wet etching. The growth region 13 and the mask 14 are stripes having a width of 2 μm and 10 μm, respectively. The stripe direction was <1-100> direction ((FIG. 1A)).
[0090]
The GaN film 15 grown in the growth region 13 is composed of gallium chloride (GaCl), which is a reaction product of gallium (Ga) and hydrogen chloride (HCl), as a group III material, and ammonia (NH) as a group V material. _Three ) A hydride VPE method using gas was used. The substrate 11 is set in a hydride growth apparatus and heated to a growth temperature of 1000 ° C. in a hydrogen atmosphere. After the growth temperature is stabilized, the HCl flow rate is supplied at 20 cc / min, NH _Three By supplying about 2000 minutes at a flow rate of 2000 cc / min, a facet structure made of the {1-101} plane of the GaN film 15 was grown in the growth region 13 (FIG. 1B).
[0091]
Further, the epitaxial growth was continued for about 20 minutes, and the GaN facet structure 15 was developed until the mask 14 was covered (FIG. 1C).
[0092]
By continuing the epitaxial growth, the facet structure was embedded (FIG. 1D), and finally a GaN film having a flat surface of about 200 μm was formed by the growth for 5 hours (FIG. 1E). After forming the GaN film 15, NH _Three While supplying the gas, cool it at room temperature and take it out from the growth apparatus.
[0093]
It was confirmed that the GaN film 15 formed according to the second example was free of cracks despite the difference in lattice constant and thermal expansion coefficient from the SiC substrate 11. Moreover, the GaN film on which the thick film has been grown has very few defects and a defect density of 10 ⁶ cm ² It was about.
[0094]
The GaN film grown in this example has very few defects, and device characteristics can be improved by growing high-quality device structures such as lasers, FETs, and HBTs thereon.
[0095]
Further, the GaN film 15 can be used as a substrate material by removing the SiC substrate 11 by polishing or the like.
[0096]
In the second embodiment, a hydride VPE method is used for epitaxial growth of a GaN film, but the same effect can be obtained by using a metal organic compound vapor deposition method (MOCVD). In this embodiment, the SiC substrate 11 is used, but the Si substrate, ZnO substrate, Al ₂ O _Three Substrate substrate, LiGaO ₂ Substrate, MgAl ₂ O _Four Even if a substrate or the like is used, the same effect can be obtained. Furthermore, although the GaN film 12 having a film thickness is formed in advance on the SiC substrate 11, a mask may be formed directly on the substrate 11.
[0097]
Further, as the mask 14, SiO ₂ However, the present invention is not limited to this. SiN _x An insulator film such as In this embodiment, the width of the mask 14 is 10 μm, but the same effect can be obtained as long as the mask can be embedded. Further, the stripe is formed in the <1-100> direction, but if a facet is formed, the direction <1-120> may be perpendicular to the direction, and even if the angle is inclined from these directions, it depends on the crystal growth conditions. A facet structure can be formed in the growth region. The crystal growth conditions for forming the facet structure vary depending on the material.
[0098]
Further, although AlGaN having an Al composition of 0.1 is used as the film on the substrate 11, this composition may be arbitrary, and the same effect can be obtained by using AlN, InGaN or the like in addition to this film. Furthermore, although the GaN epitaxial growth has been described, the same effect can be obtained by epitaxially growing an InGaN film, an AlGaN film, or an InN film. The same effect can be obtained by adding impurities to the growing group III-V compound.
[0099]
(Third embodiment)
A third embodiment of the present invention will be described with reference to FIG.
[0100]
In the third embodiment, as the substrate, (111) MgAl ₂ O _Four A substrate 21 was used. The surface of this substrate 21 is SiO ₂ A film 23 was formed and separated into a mask 23 and a growth region 22 by photolithography and wet etching. The growth region 22 and the mask 23 are stripes having a width of 4 μm and 3 μm, respectively. The stripe direction was the <11-20> direction ((FIG. 2A)).
[0101]
For the growth of the GaN film, a hydride VPE method suitable for suppressing the deposition of polycrystalline GaN on the mask 23 was used. In this method, gallium chloride (GaCl), which is a reaction product of gallium (Ga) and hydrogen chloride (HCl), is used as a group III material, and ammonia (NH) is used as a group V material. _Three ) Use gas.
[0102]
First, the substrate 21 is set in a growth apparatus, heat-treated at a high temperature of about 1000 ° C. while supplying hydrogen gas, then cooled to 500 ° C., and an HCl flow rate is supplied at 0.5 cc / min. _Three By supplying about 1000 minutes at a flow rate of 1000 cc / minute, a GaN buffer layer 24 having a thickness of about 20 nm is formed in the crystal growth region 23 (FIG. 2B).
[0103]
In this state, NH _Three The temperature is raised to 1000 ° C. while supplying gas. After the growth temperature is stabilized, the HCl flow rate is supplied at 20 cc / min, NH _Three By supplying about 1500 minutes at a flow rate of 1500 cc / min, a facet structure 25 made of GaN {1-101} plane was grown on the GaN buffer layer 24 in the growth region 22 (FIG. 2C).
[0104]
Further, the epitaxial growth is continued and the facet structure of the GaN film 25 is developed until the mask 23 is covered, and then the growth is continued while embedding the facet structure. Finally, the surface has a flat surface of about 200 μm after 5 hours of growth. A GaN film 25 was formed (FIG. 2D). After the formation of the GaN film 25, NH _Three While supplying gas, cool to room temperature and remove from the growth apparatus.
[0105]
The GaN film 25 formed by the third embodiment has MgAl ₂ O _Four It was confirmed that there were no cracks despite the difference in lattice constant and thermal expansion coefficient from the substrate 21. Moreover, the GaN film on which the thick film has been grown has very few defects and 10 ⁶ cm ² It was about.
[0106]
The GaN film grown in this example has very few defects, and device characteristics can be improved by growing high-quality device structures such as lasers, FETs, and HBTs thereon. MgAl ₂ O _Four The GaN film 25 can also be used as a substrate material by removing the substrate 21 by polishing or the like.
[0107]
In the third embodiment, a hydride VPE method is used for epitaxial growth of a GaN film, but the same effect can be obtained by using an organic metal compound vapor phase growth method (MOCVD). In the examples, MgAl ₂ O _Four Substrate 21 was used, but Si substrate, ZnO substrate, SiC substrate, LiGaO ₂ Substrate, Al ₂ O _Three Even if a substrate or the like is used, the same effect can be obtained. MgAl ₂ O _Four Although the mask is directly formed on the substrate 21, a GaN film may be formed on the substrate 21 in advance.
[0108]
Further, as the mask 14, SiO ₂ However, the present invention is not limited to this. SiN _x An insulator film such as Further, although the width of the mask 24 is 10 μm, the same effect can be obtained as long as the mask can be embedded. In this embodiment, the stripes are formed in the <11-20> direction. However, if facets are formed, the direction may be perpendicular to the direction <1-100>, and the crystal growth conditions may be inclined at an angle from these directions. Thus, a facet structure can be formed in the growth region. The crystal growth conditions for forming the facet structure vary depending on the material.
[0109]
In this embodiment, since the GaN film is grown after providing the low-temperature buffer layer on the substrate, it is possible to reduce crystal defects.
[0110]
Furthermore, in the embodiments, the epitaxial growth of GaN has been described. However, the same effect can be obtained even if an InGaN film, an AlGaN film, or an InN film is epitaxially grown. Further, the same effect can be obtained by adding impurities to the growing III-V group compound.
[0111]
(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a schematic diagram in which the shape of the growth region for selective epitaxial growth is round, triangular, and rectangular.
[0112]
In this example, (0001) plane Al is used as the substrate. ₂ O _Three A crystal substrate in which a GaN film 42 having a thickness of about 1 μm was previously formed on the substrate 41 was used.
[0113]
On the surface of the GaN film 42, SiO ₂ A film was formed and separated into a mask 43 and a growth region 44 by photolithography and wet etching. There are three types of growth regions 44: a round shape having a diameter of 4 μm (FIG. 3A), a triangular shape having a side of 3 μm (FIG. 3B), and a rectangular shape having a 5 μm square (FIG. 3C). Each mask was used.
[0114]
The GaN film 45 grown on the formed growth region 44 is composed of trimethylgallium (TMGa) and trimethylaluminum (TMAl) as a group III material and ammonia (NH) as a group V material. _Three ) An organic metal compound vapor phase growth method using a gas was used.
[0115]
FIG. 4 is a schematic view of a process of forming a group III-V compound semiconductor film by vapor deposition on the substrate on which the growth region of FIG. 3 is formed. The substrate 41 is set in an organometallic compound vapor phase growth apparatus, and hydrogen gas and NH _Three The temperature is raised to a growth temperature of 1050 ° C. while supplying gas. After the growth temperature is stabilized, the trimethylgallium flow rate is supplied at 5 cc / min, NH _Three By supplying about 10 minutes at a flow rate of 5000 cc / min, a facet structure made of the {1-101} plane of the GaN film 45 was grown in the growth region 44 (FIG. 4A).
[0116]
Further, the epitaxial growth was continued for about 30 minutes, and the facet structure of the GaN layer 45 was developed until the mask 43 was covered (FIG. 4B).
[0117]
By continuing the epitaxial growth, the facet structure of the GaN layer 45 is embedded (FIG. 4C), and finally, a GaN film 45 having a flat surface of about 100 μm is formed by the growth for 12 hours (FIG. 4 ( d)).
[0118]
It was confirmed that the GaN film 45 formed in the three types of growth regions had a flat surface regardless of the shape of the growth region, and the sapphire substrate 41 was not cracked. In this embodiment, the growth region has three shapes, round, triangular, and rectangular. However, the shape that can embed the mask region is the same regardless of the polygonal shape and size. effective.
[0119]
The GaN film grown in this example has very few defects, and device characteristics can be improved by growing high-quality device structures such as lasers, FETs, and HBTs thereon.
[0120]
Further, the GaN film 45 can be used as a substrate material by removing the sapphire substrate 41 by polishing or the like.
[0121]
In the fourth embodiment, a hydride VPE method is used for epitaxial growth of a GaN film, but the same effect can be obtained by using a metal organic compound vapor deposition method (MOCVD). Also Al ₂ O _Three Substrate 41 was used, but Si substrate, ZnO substrate, SiC substrate, LiGaO ₂ Substrate, MgAl ₂ O _Four Even if a substrate or the like is used, the same effect can be obtained. Furthermore Al ₂ O _Three Although the GaN film 42 having a film thickness is formed in advance on the substrate 41, a mask may be formed directly on the substrate 41.
[0122]
Further, as the mask 43, SiO ₂ However, the present invention is not limited to this. SiN _x An insulator film such as
[0123]
Moreover, although the GaN epitaxial growth has been described, the same effect can be obtained by epitaxially growing an InGaN film, an AlGaN film, or an InN film. Further, the same effect can be obtained by adding impurities to the growing III-V group compound.
[0124]
(Fifth embodiment)
A fifth embodiment of the present invention will be described with reference to FIG.
[0125]
As the substrate 51, a (0001) -plane sapphire substrate 51 on which a GaN film 52 having a thickness of 1 μm was formed was used.
[0126]
On the surface of this substrate 51, SiO ₂ A film was formed and separated into a first mask 53 and a first growth region 54 by photolithography and wet etching. The first growth region 54 and the first mask 53 were in the form of stripes of 2 μm and 5 μm, respectively. The stripe direction was <11-20> (FIG. 5A).
[0127]
The first GaN film 55 grown in the first growth region 54 is made of gallium chloride (GaCl), which is a reaction product of gallium (Ga) and hydrogen chloride (HCl), as a group III material, as in the first embodiment. And ammonia in group V raw materials (NH _Three ) A hydride VPE method using gas was used. The substrate 51 is set in a hydride growth apparatus and heated to a growth temperature of 1000 ° C. in a hydrogen atmosphere. The substrate 51 is NH from a temperature of 650 ° C. _Three Use a gas atmosphere. After the growth temperature is stabilized, the HCl flow rate is supplied at 10 cc / min, NH _Three The first GaN film 55 in which the first mask 53 is embedded is grown at a flow rate of 4000 cc / min for 60 minutes through the growth steps (a) to (e) of FIG. 1 described in the first embodiment. Is formed (FIG. 5B). After forming the first GaN film 55, NH _Three Cool to room temperature in a gas atmosphere and remove from the growth apparatus.
[0128]
Next, SiO is again formed on the GaN film 55. ₂ A film is formed, and a second growth region 56 and a second mask 57 are formed. The respective stripe widths were 2 μm and 5 μm, and the stripe direction was <11-20> (FIG. 5C). A second mask 57 is embedded on the substrate 51 again through the growth steps (a) to (e) of FIG. 1 described in the first embodiment, and a second GaN layer 58 of about 150 μm is formed. A flattened surface obtained by growth was obtained (FIG. 5 (d)).
[0129]
As a result of examining the defect of the grown second GaN film 58 with a cross-sectional transmission electron microscope, it was found that the defect was 10 ^Five cm ² The following were extremely few. Although the two-stage selective growth has been described here, the defect density can be further reduced by repeating the above steps.
[0130]
In the fifth embodiment, a hydride VPE method is used for epitaxial growth of a GaN film, but the same effect can be obtained by using a metal organic chemical vapor deposition method (MOCVD). Also Al ₂ O _Three Substrate 51 was used, but Si substrate, ZnO substrate, SiC substrate, LiGaO ₂ Substrate, MgAl ₂ O _Four Even if a substrate or the like is used, the same effect can be obtained. Furthermore Al ₂ O _Three Although the mask is formed after the GaN film 52 is grown on the substrate 51, the present invention is not limited to this, and the first mask 53 may be grown directly without growing the GaN film 52 on the substrate.
[0131]
Further, as a mask 53, SiO ₂ However, the present invention is not limited to this. SiN _x An insulator film such as Furthermore, although the mask patterned so that the growth region becomes a stripe is used, the present invention is not limited to this, and a round shape, a rectangular shape, or a triangular shape may be used. Moreover, although the GaN epitaxial growth has been described, the same effect can be obtained by epitaxially growing an InGaN film, an AlGaN film, or an InN film. Further, the same effect can be obtained by adding impurities to the growing III-V group compound.
[0132]
In each embodiment of the present invention, an example using a GaN-based group III-V compound semiconductor has been described. However, the present invention is not limited to this, and a group III-V compound semiconductor having a lattice constant or a thermal expansion coefficient different from that of the substrate is not limited thereto. Needless to say, it is applicable to growth.
[0133]
(Sixth embodiment)
A sixth embodiment of the present invention will be described with reference to FIG. FIG. 6 is a schematic view for explaining a process of using the epitaxial growth of the present invention for growing a GaN film and manufacturing a GaN-based semiconductor laser on the GaN film.
[0134]
A sapphire substrate 61 having a (0001) plane on which a GaN film 62 having a thickness of 1 μm was formed was used as the substrate 61 shown in FIG. The surface of the substrate 61 is SiO. ₂ A film was formed and separated into a first mask 63 and a first growth region 64 by photolithography and wet etching as in the first to fourth embodiments. The first growth region 64 and the first mask 63 were in the form of stripes of 5 μm and 2 μm, respectively. The stripe direction was tilted 10 degrees from the <11-20> direction (FIG. 6A).
[0135]
The first GaN film 65 grown in the first growth region 64 is formed of gallium chloride (GaCl), which is a reaction product of gallium (Ga) and hydrogen chloride (HCl) as a group III material, as in the first embodiment. And ammonia in group V raw materials (NH _Three ) A hydride VPE method using gas was used. The substrate 61 is set in a hydride growth apparatus and heated to a growth temperature of 1000 ° C. in a hydrogen atmosphere. The substrate 51 is NH from a temperature of 650 ° C. _Three Use a gas atmosphere. After the growth temperature is stabilized, the HCl flow rate is supplied at 40 cc / min, NH _Three Flow rate 1000cc / min, and silane (SiH _Four ) The film thickness is 200 .mu.m in which the first mask 63 is embedded through the growth steps shown in FIGS. 1A to 1E described in the first embodiment at a flow rate of 0.01 cc / min for 150 minutes. The first GaN film 65 is formed (FIG. 5B). After forming the first GaN film 65, NH _Three Cool to room temperature in a gas atmosphere and remove from the growth apparatus. The GaN film 65 is n-type and 1 × 10. ¹⁸ cm ^-3 The carrier concentration was the above.
[0136]
Next, the GaN-based semiconductor laser structure was fabricated using metal organic chemical vapor deposition (MOVPE). After the GaN film 65 is formed, it is set in an MOCVD apparatus and heated to a growth temperature of 1050 ° C. in a hydrogen atmosphere. NH from 650 ℃ _Three Use a gas atmosphere. 1 μm thick n-type GaN layer 66 to which Si is added, 0.4 μm thick n-type Al to which Si is added _0.15 Ga _0.85 N clat layer 67, 0.1 μm thick n-type GaN light guide layer 68 doped with Si, 2.5 nm thick undoped In _0.2 Ga _0.8 N quantum well layer and 5 nm thick undoped In _0.05 Ga _0.95 10-period multi-quantum well structure active layer 69 composed of an N barrier layer, 20 nm thick p-type Al doped with magnesium (Mg) _0.2 Ga _0.8 N layer 70, p-type GaN light guide layer 71 with a thickness of 0.1 μm with Mg added, p-type Al with a thickness of 0.4 μm with Mg added _0.15 Ga _0.85 An N cladding layer 72 and a p-type GaN contact layer 73 having a thickness of 0.5 μm to which Mg was added were sequentially formed to produce a laser structure. After the p-type GaN contact layer 73 is formed, HN _Three It is cooled to room temperature in a gas atmosphere and taken out from the growth apparatus (FIG. 6C). 2.5 nm thick undoped In _0.2 Ga _0.8 N quantum well layer and 5 nm thick undoped In _0.05 Ga _0.95 The multiple quantum well structure active layer 69 made of an N barrier layer was formed at a temperature of 780 ° C.
[0137]
Next, the sapphire substrate 61 on which the laser structure is formed is set in a polisher, and the sapphire substrate 61, the GaN layer 62, and SiO. ₂ The mask 63 and the GaN film 65 are polished by 50 μm to expose the GaN film 65. A titanium (Ti) -aluminum (Al) n-type electrode 74 is formed on the exposed GaN layer 65 surface, and a nickel (Ni) -gold (Au) p-type electrode 75 is formed on the p-type GaN layer 73. Is formed (FIG. 6D).
[0138]
In the laser structure shown in FIG. 6, an n-type electrode is formed on the back surface, and an element can be formed without forming an n-type electrode on the nitride surface by a complicated manufacturing process such as dry etching as in the prior art. The manufacturing process can be simplified.
[0139]
In addition, since sapphire and GaN-based semiconductors have different crystal cleavage planes, it has been difficult to form a resonator mirror having a laser structure on a conventional sapphire substrate by cleavage.
[0140]
In contrast, in this embodiment, since the GaN layer 65 with few crystal defects can be grown thickly, even if the sapphire substrate or the mask material is removed, the laser structure of the GaN-based semiconductor formed on the GaN 65 is not affected. In addition, the laser structure on the GaN layer 65 has the advantage that a resonator mirror surface can be formed by cleavage, so it is greatly simplified compared to the conventional method in which the resonator mirror surface is formed by a complicated process such as dry etching. The yield was greatly improved.
[0141]
In this embodiment, after forming a laser structure on the GaN layer 65, the sapphire substrate 51, GaN film 62, SiO ₂ The mask 63 is polished, but before the laser structure is fabricated, the sapphire substrate 61, GaN film 62, SiO ₂ The same effect can be obtained even if the mask 63 is polished.
[0142]
In this embodiment, the sapphire substrate 61, the GaN layer 62, and SiO. ₂ The n-type electrode is formed by polishing the mask 63 and a part of the GaN film 65, but the n-type electrode is removed by dry etching without polishing to form the n-type electrode. In addition, a conventional structure can be manufactured by forming a resonator mirror surface.
[0143]
【The invention's effect】
As described above, the III-V compound semiconductor growth method according to the present invention is a group III-V compound compound that grows by limiting the growth region on the substrate with a mask and promoting facet growth at the initial growth stage. A high quality III-V compound semiconductor layer can be formed by suppressing cracks caused by the difference in thermal expansion coefficient between the semiconductor layer and the substrate crystal and the difference in lattice constant and suppressing the introduction of defects. Therefore, if the crystal according to the present invention is used, a high-quality semiconductor element, for example, a laser structure or a transistor structure can be produced thereon, and it is expected that the characteristics are dramatically improved.
[Brief description of the drawings]
FIG. 1 is a process schematic diagram illustrating a method for forming a III-V compound semiconductor according to the present invention.
FIG. 2 MgAl on which an AlGaN film is formed ₂ O _Four It is the schematic of the process of forming a GaN film | membrane using a hydride VPE method on a board | substrate.
FIG. 3 is a schematic diagram in which the shape of a growth region for selective epitaxial growth is formed into a round shape, a triangular shape, and a rectangular shape.
4 is a schematic view of a step of forming a group III-V compound semiconductor film using a vapor phase growth method on a substrate on which the round, triangular, and rectangular growth regions shown in FIG. 3 are formed.
FIG. 5 is a schematic view of a GaN film formed by repeating the growth method of the present invention twice.
FIG. 6 is a schematic view of a process for forming a GaN-based semiconductor laser structure on a GaN film formed by using the growth method of the present invention.
[Explanation of symbols]
11 Substrate
12 Group III-V compound semiconductor film formed on substrate
13 Growth region for growing group III-V compound semiconductor
14 Mask
15 Epitaxially grown III-V compound semiconductor film
16 Facet structure of III-V compound semiconductor
21 (0001) sapphire substrate
22 GaN film
23 Mask
25 Epitaxially grown GaN film
31 (111) MgAl ₂ O _Four substrate
32 1 μm GaN film or AlGaN film
32 Growth region formed on substrate
33 SiO formed on the substrate ₂ Membrane mask
34 Epitaxially grown GaN buffer layer
35 GaN film grown by hydride VPE method
43 Mask
44 Growth area
51 (0001) plane sapphire substrate
53 First mask
54 First growth region
55 First GaN layer
56 Second growth area
57 second mask
58 Second GaN layer
65 n-type GaN film
66 n-type GaN layer
67 n-type Al _0.15 Ga _0.85 N clat layer
68 n-type GaN optical guide layer
69 10-period active layer with multiple quantum well structure
70 p-type Al _0.2 Ga _0.8 N layers
71 p-type GaN optical guide layer
72 p-type Al _0.15 Ga _0.85 N clat layer
73 p-type GaN contact layer
74 Ti-Al n-type electrode
75 Ni-Au p-type electrode

Claims (22)

Forming a growth region with a mask material patterned on a substrate surface having a lattice constant or a thermal expansion coefficient different from that of a GaN-based semiconductor, or a GaN-based semiconductor surface formed on the substrate; and a GaN-based semiconductor in the growth region grown to form a facet structure bent Rutotomoni rearrangement, a step of flattening the surface covering the mask material with GaN-based semiconductor grown regions adjacent stack of GaN-based semiconductor device on the GaN-based semiconductor film A method of forming a GaN-based semiconductor multilayer structure, comprising the step of forming a structure. Forming a growth region with a mask material patterned on a substrate surface having a lattice constant or a thermal expansion coefficient different from that of a GaN-based semiconductor, or a GaN-based semiconductor surface formed on the substrate; and a GaN-based semiconductor in the growth region bending Rutotomoni dislocations is grown to form a facet structure, the step of planarizing the surface covering the mask material with GaN-based semiconductor growth region adjacent at least said substrate from said GaN-based semiconductor film, the mask material A method for forming a GaN-based semiconductor multilayer structure, comprising: a removing step; and a step of forming a multilayer structure of GaN-based semiconductor elements on the GaN-based semiconductor film. Forming a growth region with a mask material patterned on a substrate surface having a lattice constant or a thermal expansion coefficient different from that of a GaN-based semiconductor, or a GaN-based semiconductor surface formed on the substrate; and a GaN-based semiconductor in the growth region grown to form a facet structure bent Rutotomoni rearrangement, a step of flattening the surface covering the mask material with GaN-based semiconductor grown regions adjacent stack of GaN-based semiconductor device on the GaN-based semiconductor film A method for forming a GaN-based semiconductor multilayer structure, comprising: forming a structure; and removing at least the substrate and mask material from the GaN-based semiconductor film.   The method for forming a GaN-based semiconductor multilayer structure according to claim 1, wherein the GaN-based semiconductor element is a GaN-based semiconductor light-emitting element including a double heterostructure.   5. The method for forming a GaN-based semiconductor multilayer structure according to claim 4, wherein the GaN-based light emitting device is a GaN-based semiconductor laser. A substrate having a lattice constant or thermal expansion coefficient different from that of a GaN-based semiconductor, a patterned mask material for forming a growth region on the substrate surface or a GaN-based semiconductor surface formed on the substrate, and a facet structure in the growth region grown while forming a bent dislocations, covering the mask material with GaN-based semiconductor grown growth region GaN-based semiconductor is adjacent the facet structure is planarized buried further by the GaN-based semiconductor growth A GaN-based semiconductor multilayer structure, wherein a multilayer structure of GaN-based semiconductor elements is formed on the planarized GaN-based semiconductor film. The GaN-based semiconductor multilayer structure according to claim 6 , wherein at least the substrate and the mask material are removed from the GaN-based semiconductor multilayer structure.   The GaN-based semiconductor multilayer structure according to claim 6 or 7, wherein the GaN-based semiconductor element is a GaN-based semiconductor light-emitting element including a double hetero structure.   9. The GaN-based semiconductor multilayer structure according to claim 8, wherein the GaN-based light emitting device is a GaN-based semiconductor laser. Forming a growth region with a mask material patterned on a substrate surface having a lattice constant or a thermal expansion coefficient different from that of a GaN-based semiconductor, or a GaN-based semiconductor surface formed on the substrate; and a GaN-based semiconductor in the growth region grown to form a facet structure bent Rutotomoni rearrangement, a step of flattening the surface covering the mask material with GaN-based semiconductor grown regions adjacent, GaN-based on the planarized GaN-based semiconductor film on A method of manufacturing a GaN-based semiconductor element, comprising a step of forming a semiconductor element. Forming a growth region with a mask material patterned on a substrate surface having a lattice constant or a thermal expansion coefficient different from that of a GaN-based semiconductor, or a GaN-based semiconductor surface formed on the substrate; and a GaN-based semiconductor in the growth region bending Rutotomoni dislocations is grown to form a facet structure, the step of planarizing the surface covering the mask material with GaN-based semiconductor growth region adjacent at least said substrate from said GaN-based semiconductor film, the mask material A method of manufacturing a GaN-based semiconductor device, comprising: a removing step; and a step of forming a GaN-based semiconductor device on the planarized GaN-based semiconductor film. Forming a growth region with a mask material patterned on a substrate surface having a lattice constant or a thermal expansion coefficient different from that of a GaN-based semiconductor, or a GaN-based semiconductor surface formed on the substrate; and a GaN-based semiconductor in the growth region grown to form a facet structure bent Rutotomoni rearrangement, a step of flattening the surface covering the mask material with GaN-based semiconductor grown regions adjacent, GaN-based on the planarized GaN-based semiconductor film on A method of manufacturing a GaN-based semiconductor element, comprising: forming a semiconductor element; and removing at least the substrate and mask material from the GaN-based semiconductor film. The GaN-based semiconductor device manufacturing method of the GaN-based semiconductor device according to any one of claims 10 to 12, characterized in that a GaN-based semiconductor light-emitting device comprising a double heterostructure.   14. The method for manufacturing a GaN-based semiconductor device according to claim 13, wherein the GaN-based light emitting device is a GaN-based semiconductor laser. A substrate having a lattice constant or thermal expansion coefficient different from that of a GaN-based semiconductor, a patterned mask material for forming a growth region on the substrate surface or a GaN-based semiconductor surface formed on the substrate, and a facet structure in the growth region grown while forming a bent dislocations, covering the mask material with GaN-based semiconductor grown growth region GaN-based semiconductor is adjacent the facet structure is planarized buried further by the GaN-based semiconductor growth A GaN-based semiconductor element, wherein a GaN-based semiconductor element is formed on the GaN-based semiconductor film and the planarized GaN-based semiconductor film.   The GaN-based semiconductor device according to claim 15, wherein at least the substrate and the mask material are removed from the GaN-based semiconductor device.   The GaN-based semiconductor device according to claim 15 or 16, wherein the GaN-based semiconductor device is a GaN-based semiconductor light-emitting device including a double hetero structure.   The GaN-based semiconductor device according to claim 17, wherein the GaN-based light emitting device is a GaN-based semiconductor laser.   6. The method for forming a GaN-based semiconductor multilayer structure according to claim 4, wherein the GaN-based semiconductor light emitting device has an undoped quantum well active layer.   The GaN-based semiconductor multilayer structure according to claim 8 or 9, wherein the GaN-based semiconductor light-emitting device has an undoped quantum well active layer.   The GaN-based semiconductor light-emitting device according to claim 13 or 14, wherein the GaN-based semiconductor light-emitting device has an undoped quantum well active layer.   The GaN-based semiconductor light-emitting device according to claim 17 or 18, wherein the GaN-based semiconductor light-emitting device has an undoped quantum well active layer.

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