JP2002100575A - Low defect nitride semiconductor substrate and its fabricating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nitride semiconductor for use in a light emitting element, e.g. a light emitting diode or a laser diode, or a light receiving element, e.g. a solar cell or a photosensor, and a method for growing a low defect nitride semiconductor substrate comprising a nitride semiconductor. SOLUTION: A first protective film is formed in pattern on a different kind of substrate and a nitride semiconductor is grown at the window part of the protective film. Subsequently, the first protective film is removed and a nitride semiconductor layer is grown in the lateral direction using the nitride semiconductor as a nucleus. Furthermore, a second protective film is formed in pattern thereon, a nitride semiconductor is grown at the window part of the protective film, the second protective film is removed and a nitride semiconductor layer is grown in the lateral direction using the nitride semiconductor as a nucleus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light emitting diode,
A nitride semiconductor (In) used for a light emitting element such as a laser diode or a light receiving element such as a solar cell or an optical sensor.
_{x Al y Ga 1-xy N} , 0 ≦ X, 0 ≦ Y, relates growing method of X + Y ≦ 1) nitride semiconductor device consisting, on the Growth method for particular growing a nitride semiconductor of low defect on the substrate.

[0002]

2. Description of the Related Art In recent years, light-emitting diodes (LEDs) and semiconductor lasers (LDs) using nitride semiconductor devices have been actively studied, and high-intensity light-emitting diodes (LEs) have been developed.
D) and a semiconductor laser (LD) capable of continuous oscillation at room temperature have been realized. A general method for forming such a nitride semiconductor device is to use a different kind of substrate such as sapphire, spinel, and silicon carbide different from a nitride semiconductor, on which a nitride semiconductor does not grow via a buffer layer. Alternatively, a method is known in which a protective film made of a material that is difficult to grow, such as SiO _2, is grown into a stripe shape, and a nitride semiconductor is selectively grown thereon. Further, sapphire, spinel, using a different substrate different from the nitride semiconductor such as silicon carbide, growing a nitride semiconductor to be an underlying layer thereon, and partially forming the nitride semiconductor in a stripe shape,
There is known a method of selectively growing a nitride semiconductor on a side surface of a formed underlayer while utilizing the lateral growth of the nitride semiconductor on the underlayer. These are methods for growing a nitride semiconductor in the lateral direction, which can reduce dislocations generated due to a difference in lattice constant when a nitride semiconductor device is grown on a heterogeneous substrate, and is epitaxially laterally overgrown: ELOG). The nitride semiconductor substrate obtained by such a growth method is different from the conventional nitride semiconductor growth method.
A nitride semiconductor substrate with low defects can be expected.

[0003] For example, Jpn. J. Appl. Phys
s. Vol. 37 (1988) pp. L309-L31
No. ₂ discloses that a protective film such as SiO ₂ is partially formed on gallium nitride grown on a sapphire substrate, and new gallium nitride is grown thereon.
Since gallium nitride does not directly grow on SiO ₂ , gallium nitride exposed at the window of the protective film becomes a growth nucleus, and gallium nitride grows laterally in a region above the protective film. Therefore, gallium nitride having a low dislocation density can be grown on the SiO2 protective film.

Japanese Patent Application Laid-Open No. 11-145516 discloses that instead of forming a SiO ₂ protective film, an AlGaN layer grown on a silicon substrate is etched in a stripe shape to partially expose the silicon substrate. Disclosed above is a method of growing gallium nitride. Since gallium nitride does not grow epitaxially on a silicon substrate, gallium nitride grows laterally epitaxially with a stripe-shaped AlGaN layer as a growth nucleus. Therefore, gallium nitride having a low dislocation density can be grown on the exposed portion of the silicon substrate.

According to these ELOG growth methods, the crystal defect density can be reduced by two orders of magnitude or more as compared with a nitride semiconductor layer grown using a conventional buffer layer.
Therefore, by forming various nitride semiconductor devices such as an LED device, an LD device, and a light receiving device on the nitride semiconductor substrate manufactured by these ELOG growth methods, the life characteristics of the nitride semiconductor device are dramatically improved. Can be improved. For example, a gallium nitride-based compound semiconductor laser manufactured using a gallium nitride substrate grown by ELOG can achieve continuous oscillation for 10,000 hours or more.

[0006]

However, in the above-mentioned growth method, when a nitride semiconductor is formed on a substrate, crystal defects generated in the nitride semiconductor layer on the protective film are reduced, There is a problem that the nitride semiconductor grown on the substrate deteriorates crystallinity due to decomposition of the protective film.

In this growth method, when a nitride semiconductor is grown on a protective film such as silicon oxide, the silicon oxide may be decomposed, and when the silicon oxide is decomposed,
The nitride semiconductor may grow abnormally on the silicon oxide or the crystallinity of the nitride semiconductor may be reduced. On the other hand, when growing a nitride semiconductor at a low temperature to suppress the decomposition of silicon oxide, it is difficult to obtain a single crystal of the nitride semiconductor,
The crystallinity of the nitride semiconductor layer decreases.

In the above-mentioned growth method described later, since a protective film such as silicon oxide is not provided at the time of growth of the nitride semiconductor, a decrease in crystallinity due to decomposition of the protective film can be eliminated. Further, a stripe-shaped nucleus is formed by etching the AlGaN layer, and gallium nitride is laterally grown from the nucleus, whereby a low-defect nitride semiconductor layer can be obtained. However, since the end surface of the striped AlGaN serving as a nucleus formed by etching is not good in shape, a junction formed at the time of lateral growth of gallium nitride may be enlarged. Since the junction between gallium nitrides is a portion where defects are concentrated, there has been a problem that the crystallinity of the nitride semiconductor is reduced due to the enlargement of the junction with many defects.

Accordingly, an object of the present invention is to provide an EL
It is an object of the present invention to provide a nitride semiconductor substrate which has better crystallinity and improved mass productivity than a nitride semiconductor substrate manufactured by OG growth and can form an excellent light emitting element and light receiving element. .

[0010]

In order to achieve the above object, a nitride semiconductor substrate according to the present invention comprises a step of forming a first protective film in a pattern on a different kind of substrate from a nitride semiconductor. Growing a first seed crystal made of a nitride semiconductor in a window portion of the first protective film, and removing the first protective film, so that the first seed crystal made of a nitride semiconductor is periodically removed. Forming a stripe-shaped, lattice-shaped, island-shaped, or polygonal column, growing the first nitride semiconductor layer on the entire surface of the substrate, covering the first seed crystal, On the nitride semiconductor layer of
Forming a second protective film in a pattern shape; and growing a second seed crystal made of a nitride semiconductor in a window of the second protective film, and removing the second protective film to form a nitride film. Forming a second seed crystal made of a compound semiconductor into a periodic stripe, lattice, island, or polygonal column shape, and forming a second nitride over the entire surface of the substrate so as to cover the second seed crystal. Growing a semiconductor layer.

In the present invention, a second protective film is preferably formed in a pattern on the first seed crystal and on the junction between the first nitride semiconductors.

In the present invention, as the first and second protective films, a metal having a melting point of 1200 ° C. or more, silicon oxide,
Silicon nitride, titanium oxide, zirconium oxide, a multilayer film thereof, or the like can be used.

In the present invention, sapphire, spinel, or silicon carbide can be used for the heterogeneous substrate.

In the present invention, the ratio Ww / Ws of the width (Ws) of the first seed crystal to the width (Ww) of the window portion of the first seed crystal is 1 to 20.

In the present invention, the thickness of the second seed crystal is 5 μm or more.

In the present invention, the second nitride semiconductor layer has a cavity above the first seed crystal and above a junction between the first nitride semiconductors.

A first seed crystal made of a nitride semiconductor formed at regular intervals in a columnar shape having periodic stripes, lattices, islands, or polygons on a heterogeneous substrate different from the nitride semiconductor; A first nitride semiconductor layer formed on the entire surface of the substrate so as to cover the first seed crystal, and a periodic stripe, lattice, island, or polygon is formed on the first nitride semiconductor layer. A second seed crystal made of a nitride semiconductor formed in a columnar shape and a second nitride semiconductor layer formed so as to cover the second seed crystal. It is a nitride semiconductor substrate having a cavity.

In the present invention, the second seed crystal is formed avoiding the upper portion of the first seed crystal and the upper portion of the junction between the first nitride semiconductors.

In the present invention, the ratio (Ww / Ws) of the width (Ws) of the first seed crystal to the width (Ww) of the window of the first seed crystal is 1 to 20, and the second seed crystal is formed. Is 5 μm or more.

In the nitride semiconductor substrate obtained by the above-described manufacturing method, a protective film having a window is formed instead of forming a seed crystal made of a nitride semiconductor by etching, and a seed film is formed in the window of the protective film. A seed crystal serving as a nucleus is formed by growing a crystal and then removing only the protective film. Thereby, the nitride semiconductor layer can be grown from the seed crystal without deteriorating the end face of the seed crystal made of the nitride semiconductor. for that reason,
End face shape is better than when a seed crystal serving as a nucleus for growing a nitride semiconductor layer is formed by etching, and the number and width of crystal defects formed at a junction between nitride semiconductors grown in the lateral direction are reduced. can do. Furthermore, the second
Is formed and the second nitride semiconductor layer is grown, so that a nitride semiconductor substrate with lower defects can be obtained. This is because the second seed crystal is formed on the nitride semiconductor in the range of good crystallinity of the first nitride semiconductor layer. In the first nitride semiconductor layer, the upper part of the first seed crystal and the junction between the first nitride semiconductors are:
Since crystal defects are concentrated, a second seed crystal is formed avoiding this range. Further, when growing the second nitride semiconductor layer, since the second seed crystal in the form of a stripe has a cavity in the window, dislocations of crystal defects do not extend in the second nitride semiconductor layer, and A nitride semiconductor substrate having good properties can be obtained.

When the thickness of the second seed crystal is 5 μm or more, a cavity can be formed in the window of the second seed crystal after the growth of the second nitride semiconductor layer. For this reason,
The second nitride semiconductor layer can prevent propagation of dislocations from the window of the second seed crystal having many crystal defects. Further, the presence of the cavity can reduce the warpage of the substrate.

Further, a metal having a melting point of 1200 ° C. or more, silicon oxide, silicon nitride, titanium oxide, zirconium oxide, or a multilayer film thereof is used for the protective film. These protective film materials have such a property that a nitride semiconductor does not grow or hardly grows on the surface thereof. Therefore, the nitride semiconductor can be grown on the window of the protective film without growing the nitride semiconductor on the protective film.

The ratio Ww / Ws of the width (Ws) of the first seed crystal to the width (Ww) of the window of the first seed crystal is 1 to 5.
By adjusting the number to be 20, the dislocation of crystal defects can be reduced. This is because crystal defects are concentrated on the first seed crystal, and by increasing the width of the window of the first seed crystal, the first nitride that grows laterally from the first seed crystal is formed. A semiconductor can be obtained with good crystallinity.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 6 is a cross-sectional view schematically showing a nitride semiconductor grown on a heterogeneous substrate obtained by the growth method of the present invention. A first protective film 2 is formed on a heterogeneous substrate 1, a window for growing a seed crystal is formed in a pattern shape, and a buffer layer (shown in the figure) is formed through the window of the first protective film 2. Not performed), the first seed crystal 3
After that, only the first protective film 2 is removed, and the first nitride semiconductor layer 4 is grown laterally with the first seed crystal 3 as a nucleus. Further, the first nitride semiconductor layer 4
Similarly to the first protective film 2, a second protective film 5 is patterned and a second seed crystal 6 is grown from a window of the second protective film 5, and then a second protective film is formed. Remove only 5,
Second nitride semiconductor layer 7 with second seed crystal 6 as a nucleus
A nitride semiconductor substrate by growing GaN laterally

[0026] Here, the first seed crystal 3, the first nitride semiconductor layer 4, the second seed crystal 6, the second nitride semiconductor layer 7 are both formula In _x Al _y Ga _{1- xy} N (0
≦ x, 0 ≦ y, x + y ≦ 1), and these may have different compositions.

Further, the first seed crystal 3, the first nitride semiconductor layer 4, the second seed crystal 6, and the second nitride semiconductor layer 7 are undoped (doped with no impurities, undoped). , A nitride semiconductor doped with an n-type impurity such as Si or a p-type impurity such as Mg can be used.

As the first protective film 2 and the second protective film 5, those having a property such that a nitride semiconductor does not grow or hardly grow on the surface are used.

Further, since the second seed crystal 6 is formed so as not to cover the first seed crystal and the junction between the first nitride semiconductor layers 4, the second seed crystal 6 has crystal defects. Nucleus with less.

The first seed crystal 3 is placed on the heterogeneous substrate 1.
By growing the buffer layer before growing
It is possible to alleviate lattice mismatch between a heterogeneous substrate and a nitride semiconductor, reduce crystal defects, and obtain a nitride semiconductor with good surface morphology.

FIGS. 1 to 6 are sectional views showing a method of growing a nitride semiconductor according to an embodiment. less than,
A method for growing a nitride semiconductor according to one embodiment of the present invention and suitable materials will be described.

First, as shown in FIG. 1, a first protective film 2 is formed on a heterogeneous substrate 1 by a method such as CVD, sputtering or vapor deposition. In the present invention, the heterogeneous substrate 1 includes (0001) plane [C plane], (11-
02) Insulation such as sapphire having any one of [R-plane] and (112-0) -plane [A-plane] as a main surface, and spinel (MgAl ₂ O ₄ ) having a (111) -plane as a main surface. Substrate, SiC (including 6H, 4H, 3C), other Zn
Substrate materials different from nitride semiconductors, such as S, ZnO, Si, and oxide substrates lattice-bonded with nitride semiconductors, can be used. Here, when the substrate 1 is sapphire having a (0001) plane [C-plane] as a main surface, the first protective film 2
Has a stripe shape perpendicular to the (112-0) plane [A plane] of the sapphire [the stripe is formed in the vertical direction on the (101-0) [M plane] of the nitride semiconductor ], And the (112-0) plane [A
Surface], the first protective film 2 preferably has a stripe shape perpendicular to the (11-02) plane [R-plane] of the sapphire. When the spinel has a (111) plane as a main surface, the first protective film 2 preferably has a stripe shape perpendicular to the (110) plane of the spinel. Further, in the growth method of the present invention, a substrate in which the main surface of the material to be the heterogeneous substrate 1 is off-angled, or a substrate in which the material is off-angled in a step shape can be used.

Next, the first protective film 2 is preferably made of a material on which a nitride semiconductor does not grow or hardly grows. As a specific example, silicon oxide (SiO 2)
_x ), silicon nitride (SiN _x , titanium oxide (TiO _x ),
Zirconium oxide (ZrO _x ), a metal film having a melting point of 1200 ° C. or more can be used in addition to these multilayer films. Further, the thickness of the first protective film 2 is not particularly limited, but is preferably 2 μm to 5 μm because the nitride semiconductor is more easily grown from the window.

In the case where the first protective film is formed in a stripe shape, the stripe width of the first protective film is not particularly limited, but a window of the first protective film for growing a seed crystal. Part width is preferably 2 μm to 10
μm, more preferably 3 μm to 5 μm, and the width of the first protective film is 10 μm to 18 μm, preferably 15 μm.
μm to 17 μm.

After the first protective film is patterned by etching, the end face of the protective film roughened by the etching is wet-etched, whereby the roughness of the end face of the protective film can be eliminated. This makes it possible to improve the crystal characteristics, particularly the end face shape, of the first seed crystal grown from the window of the first protective film.

Next, as shown in FIG. 2, a buffer layer (not shown) and a first seed crystal 3 are grown on the window of the first protective film 2 by a method such as MOCVD. Only the protective film of No. 1 is removed. First, after a first protective layer 2 is formed on a heterogeneous substrate 1, a buffer layer is grown. As the buffer layer, a layer grown at a lower temperature than the first seed crystal 3 is preferable. For example, AlN, Ga
N, AlGaN, InGaN, or the like is used, and is grown at a temperature of 900 ° C. or less and 300 ° C. or more and a film thickness of 0.5 μm to 10 Å. When the buffer layer is formed on the heterogeneous substrate 1 at a temperature of 900 ° C. or less as described above, lattice mismatch between the heterogeneous substrate 1 and the first seed crystal 3 is reduced, and the crystal defects of the first seed crystal 3 are reduced. Is preferred.

Next, the first seed crystal 3 is grown on the buffer layer grown on the window of the protective film. This first
Undoped GaN, GaN doped with an n-type impurity, or GaN doped with a p-type impurity can be used as the seed crystal 3. Further, the first seed crystal 3 is preferably grown at a higher temperature than the buffer layer, specifically, at 900 to 1100 ° C., more preferably at 1 ° C.
It is grown at 050 ° C., and the film thickness is not particularly limited, but is preferably 1 to 5 μm, more preferably 2 to 3 μm. Growing the first seed crystal with a film thickness in this range is preferable because warpage and abnormal growth of the substrate can be suppressed. Further, after growing the first seed crystal 3, only the first protective film 2 is removed to form the nucleus shown in FIG.

Next, as shown in FIG. 3, the first nitride semiconductor layer 4 is grown using the first seed crystal 3 as a nucleus under the same growth conditions as the first seed crystal. As the first nitride semiconductor layer 4, undoped GaN, GaN doped with an n-type impurity, or GaN doped with a p-type impurity can be used, and the first seed crystal 3 is used as a nucleus in the lateral direction. Let it grow. First nitride semiconductor layer 4
Is preferably 5 to 20 μm, more preferably 7 to 15 μm. If the film thickness is smaller than this range, the uppermost surface of the first nitride semiconductor 4 cannot be completely grown, so that a gap is formed and a mirror surface cannot be obtained. Further, when the film is grown with a thickness larger than this range, the substrate is warped, and there is a problem that crystal defects are diffused.

After growing the first nitride semiconductor 4, as shown in FIG. 4, a second protective film 5 is formed under the same film forming conditions as the first protective film 2, and a window is formed by etching. The pattern shape to have is formed. The film forming conditions of the second protective film 5 are not particularly limited, but may be the same as the film forming conditions of the first protective film.
μm, and more preferably 6 to 8 μm. Here, the second protective film 5 is patterned so as to cover the upper part of the first seed crystal and the junction of the first nitride semiconductor, and the second protective film 5 on which the second seed crystal grows later. It is preferable that the window portions are formed at equal intervals. The second protective film 5 is also a first protective film.
Similarly to the above protective film, after the window is formed by etching such as RIE, the end face shape of the second protective film 5 is improved by wet etching.

Next, the second seed crystal 6 is grown from the window of the second protective film 5 under the same conditions as the first seed crystal. Here, the film thickness of the second seed crystal 6 is such that when the second nitride semiconductor layer is grown in a later step, the second seed crystal 6 has a shape having a cavity in the window of the second seed crystal 6. The thickness is not particularly limited as long as it is 5 to 10 μm, preferably 5 to 7 μm. Thereafter, as shown in FIG. 5, only the second protective film is removed.
It is not necessary to completely remove it, and it may be left if the film thickness is 1 μm or less.

Next, as shown in FIG. 6, a second nitride semiconductor layer 7 is grown using the second seed crystal 6 as a nucleus.
Although growth conditions are not particularly limited, it is possible to obtain a nitride semiconductor substrate having low defects and uniform defects and having a mirror-like uppermost surface by growing under the same conditions as the first nitride semiconductor layer 4. it can. Here, the thickness of the second nitride semiconductor layer 7 is preferably 5 to 30 μm, more preferably 7 to 15 μm.

In the method for growing a nitride semiconductor according to the present invention, the first seed crystal 3, the first nitride semiconductor layer 4, the second seed crystal 6, the second nitride semiconductor, and other nitride semiconductors are removed. The growth method is not particularly limited, but includes MOVPE (metalorganic vapor phase epitaxy), HVPE (halide vapor phase epitaxy), MBE (molecular beam epitaxy), MOCVD (metal organic chemical vapor phase epitaxy), and the like. All known methods for growing nitride semiconductors can be applied. As a preferred growth method, a film thickness of 100 m
In the following, the growth rate can be easily controlled by using the MOCVD method. The MOVPE method is preferable because crystals can be grown cleanly. However, since the MOVPE method takes time, the HVPE method is preferable when a thick film is grown.

Further, the nitride semiconductor substrate of the present invention is a low-defect and uniform defect obtained by the manufacturing method described above, and is a nitride semiconductor substrate in which propagation of crystal defects is suppressed. When a nitride semiconductor device having an element structure including at least an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer is manufactured thereon, good life characteristics can be obtained and the yield can be improved. It is preferable.

[0044]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. [Embodiment 1] Each step in Embodiment 1 will be described with reference to FIGS. Although the first embodiment shows the MOCVD method, the method of the present invention is not limited to the MOCVD method. For example, an HVPE method, an MBE method, or a method of growing a nitride semiconductor can be applied.

As the substrate 1, a sapphire substrate having a 2-inch φ, C-plane as a main surface and an orientation flat surface as an A-plane is used. On this sapphire substrate, a CVD apparatus is used. ₂ was formed in a thickness of 4 [mu] m, then, the first protective film stripe width 17μm by dry etching as shown in FIG. 1, and a stripe-shaped window portion 3 [mu] m, further, eliminating roughness by wet etching the edge face.

Next, as shown in FIG.
Then, a buffer layer (not shown) made of GaN is formed on the window of the protective film using hydrogen as a carrier gas, ammonia and TMG (trimethylgallium) as a source gas.
Is grown to a thickness of 200 angstroms. After the growth of the buffer layer, only TMG is stopped, and the temperature is raised to 1050 ° C. A seed crystal 3 is grown on the buffer layer to a thickness of 3 μm.

Next, after growing the first seed crystal 3, buffered hydrofluoric acid (BHF) is formed by wet etching.
Is used to remove only the first protective film 2. By removing the first protective film 2, a first seed crystal 3 having a stripe shape serving as a nucleus can be formed.

Thereafter, as shown in FIG. 3, a first nitride semiconductor layer 4 made of undoped GaN is grown at a temperature of 1050 ° C. using TMG and ammonia as source gases to a thickness of 10 μm.

Next, as shown in FIG. 4, a second protective film 5 is formed on the first nitride semiconductor
After forming a film with a thickness of 5 μm, the width of the protective film is 5 μm, and the width of the window of the protective film is 5 μm.
A stripe is formed with a thickness of μm.

Next, a second seed crystal 6 is formed in a window portion of the second protective film 5 to a thickness of 5 μm by the MOCVD apparatus under the same conditions as the first seed crystal, and then only the second protective film 5 is formed. First
Is removed such that the nitride semiconductor layer 4 is exposed.

Next, as shown in FIG. 6, a second nitride semiconductor layer 7 is grown to a thickness of 15 μm using the second seed crystal as a nucleus.

The nitride semiconductor substrate obtained as described above has extremely reduced crystal defects, and has a high output L
It can be used for a substrate such as D.

[Embodiment 2] In Embodiment 1, the second
After removing the second protective film after growing the seed crystal,
A nitride semiconductor substrate is grown in the same manner except that a second nitride semiconductor layer is grown with the second protective film remaining 0.5 μm thick. With the nitride semiconductor obtained by the above method, a nitride semiconductor having low defects and uniform defects can be obtained as in the first embodiment.

[Embodiment 3] In the first and second embodiments, when growing the second nitride semiconductor, 5 × 10 ¹⁷ / cm ^{3 of} Si, which is an n-type impurity, is doped simultaneously with the growth. A nitride semiconductor is grown in the same manner except that the nitride semiconductor is grown to a thickness of 15 μm. With the obtained nitride semiconductor, a nitride semiconductor with low defects and uniform defects can be obtained as in Example 1.

Fourth Embodiment In the first and second embodiments, when growing the second nitride semiconductor, Mg, which is a p-type impurity, is doped at 5 × 10 ¹⁷ / cm ³ simultaneously with the growth. A nitride semiconductor is grown in the same manner except that the nitride semiconductor is grown to a thickness of 15 μm. With the obtained nitride semiconductor, a nitride semiconductor with low defects and uniform defects can be obtained as in Example 1.

[0056]

As described above, the present invention reduces the crystal defects by improving the shape of the end face of the seed crystal serving as the nucleus of the nitride semiconductor grown on the substrate and performing the lateral growth in two stages. A nitride semiconductor having good crystallinity and uniform defects can be obtained. Furthermore, when a device structure is grown using the nitride semiconductor obtained by the present invention as a substrate, a nitride semiconductor having good device performance such as life characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a nitride semiconductor substrate obtained in one step of the production of the present invention.

FIG. 2 is a cross-sectional view schematically showing a nitride semiconductor substrate obtained in one step of the production of the present invention.

FIG. 3 is a cross-sectional view schematically showing a nitride semiconductor substrate obtained in one step of the production of the present invention.

FIG. 4 is a cross-sectional view schematically showing a nitride semiconductor substrate obtained in one step of the production of the present invention.

FIG. 5 is a cross-sectional view schematically showing a nitride semiconductor substrate obtained in one step of the production of the present invention.

FIG. 6 is a cross-sectional view schematically showing a nitride semiconductor substrate obtained in one step of the production of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Different substrate 2 ... 1st protective film 3 ... 1st seed crystal 4 ... 1st nitride semiconductor layer 5 ... 2nd protective film 6 ... 2nd Seed crystal 7 of the second nitride semiconductor layer

Continued on the front page F term (reference) 4G077 AA03 BE15 DB08 ED06 EE05 EE07 EF01 5F041 AA40 CA34 CA40 CA65 5F045 AA04 AB09 AB14 AB17 AB18 AB32 AC08 AC12 AD07 AD08 AD09 AD10 AD11 AD12 AD13 AD14 AD15 AF02 AF03 AF06 AF09 CA13 AF20 DA53 HA12 5F049 MA01 MB07 PA04 SS07 5F073 CA01 CB05 DA05 EA24

Claims (12)

[Claims] A step of forming a first protective film in a pattern on a different substrate different from the nitride semiconductor; and forming a first seed crystal made of a nitride semiconductor in a window of the first protective film. Growing and removing the first protective film to form a first seed crystal serving as a nucleus in a periodic stripe shape, lattice shape or island shape, or in a column shape having a polygonal shape; Growing a first nitride semiconductor layer over the entire surface of the substrate so as to cover the seed crystal; forming a second protective film in a pattern on the first nitride semiconductor layer; A second seed crystal made of a nitride semiconductor is grown in the window of the protective film, and the second protective film is removed to form a second seed crystal serving as a nucleus in a periodic stripe shape, lattice shape or A step of forming islands and pillars having a polygonal shape; The second covering the seed crystal, the nitride semiconductor substrate manufacturing method that includes a step of growing a second nitride semiconductor layer on the entire surface of the substrate. 2. The nitride semiconductor according to claim 1, wherein the second protective film is patterned on an upper portion of the first seed crystal and an upper portion of a junction between the first nitride semiconductors. Substrate manufacturing method. 3. The method according to claim 1, wherein the protective film is made of one of a metal having a melting point of 1200 ° C. or higher, silicon oxide, silicon nitride, titanium oxide, zirconium oxide, and a multilayer film of these. A method for manufacturing a nitride semiconductor substrate according to claim 1. 4. The method according to claim 1, wherein the heterogeneous substrate is sapphire, spinel or silicon carbide. 5. The method according to claim 1, wherein a width (Ws) of said first seed crystal and a width of said first seed crystal are different from each other.
The ratio Ww / Ws to the width (Ww) of the window portion of the seed crystal is
The method for manufacturing a nitride semiconductor substrate according to claim 1, wherein the number is 1 to 20. 6. The method according to claim 1, wherein the thickness of the second seed crystal is 5 μm or more. 7. The nitride according to claim 1, wherein the second nitride semiconductor layer has a cavity above a first seed crystal and above a junction between the first nitride semiconductors. A method for manufacturing a semiconductor substrate. 8. A first semiconductor comprising a nitride semiconductor formed at regular intervals in a periodic stripe, grid, island or polygonal column shape on a heterogeneous substrate different from the nitride semiconductor.
A first nitride semiconductor layer formed on the entire surface of the substrate so as to cover the first seed crystal; and a periodic stripe, lattice, or A second seed crystal made of a nitride semiconductor formed in a pillar shape having an island shape and a polygon, and a second nitride semiconductor layer formed so as to cover the second seed crystal, wherein the second seed A nitride semiconductor substrate having a cavity between crystals. 9. The nitride semiconductor substrate according to claim 8, wherein said different kind of substrate is sapphire, spinel or silicon carbide. 10. The nitride according to claim 8, wherein the second seed crystal is formed so as to avoid an upper portion of the first seed crystal and an upper portion of a junction between the first nitride semiconductors. Semiconductor substrate. 11. The ratio of the width (Ws) of the first seed crystal to the width (Ww) of the window of the first seed crystal is Ww / Ws.
10. The nitride semiconductor substrate according to claim 8, wherein the number is 1 to 20. 12. The film thickness of the second seed crystal is 5 μm.
9. The nitride semiconductor substrate according to claim 8, wherein: