JPH1192296A - Substrate for growing gallium nitride crystal and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for growing a GaN crystal capable of producing a thick high-quality GaN crystal substrate free from defects such as dislocation and provide a process for producing a GaN crystal substrate by using the above substrate. SOLUTION: A mask layer 2 is formed on a surface of a base substrate 1 enabling the growth of a GaN crystal, plural openings 4 are formed on the upper face of the mask layer and the surface of the base substrate is exposed at the bottom in the openings. The arrangement pattern of the openings on the upper surface of the mask layer is a pattern to position the openings on the crossing points of a mesh having a quadrate form S1 as the smallest constituent unit. The quadrate S1 has a parallelogramic form or a square form devoid of the side of the (11-20) direction of the GaN crystal growing on the base substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a GaN-based crystal growth substrate and a method for manufacturing a GaN-based crystal substrate using the same.

[0002]

2. Description of the Related Art A general GaN-based semiconductor crystal (hereinafter referred to as G
As a method of growing a thick film of (aN-based crystal), there is a method of forming a buffer layer of ZnO or the like on a sapphire substrate and growing the GaN-based crystal on the buffer layer by hydride vapor phase epitaxial growth (hereinafter, HVPE). As an improved technology, spinel, LG,
There are a method of using a substrate of O, LAO, ZnO, SiC, or the like, a method of using an easily cleavable substrate, a method of providing a mask on the substrate surface, and performing selective growth thereon.

[0003]

SUMMARY OF THE INVENTION However, GaN
When the system-based crystal grows in a thick film, a large stress is applied to the interface due to the difference in lattice constant and thermal expansion coefficient between the GaN-based crystal and the sapphire substrate, and there is a problem that the GaN-based crystal is broken and a large substrate cannot be obtained. . Further, there is a problem that only a substrate having an extremely large dislocation density (1 × 10 ⁹ cm ⁻² to 1 × 10 ¹⁰ cm ⁻² ) can be obtained. Here, dislocations are defects that occur when a semiconductor layer is grown on a substrate in a state where lattice constants do not match (lattice mismatch), and these dislocations are crystal defects. When the GaN-based semiconductor material is used for a light-emitting element, it functions as a non-radiative recombination center or functions as a current path and causes a leakage current.

The present invention relates to a GaN-based crystal growth substrate capable of obtaining a high-quality GaN-based crystal substrate which is thick and does not include defects such as dislocations, and a method of manufacturing a GaN-based crystal substrate using the same. The purpose is to provide.

[0005]

SUMMARY OF THE INVENTION The present invention has the following features. (1) A mask layer is provided on a surface of a base substrate on which a GaN-based crystal can be grown, and the mask layer is made of a material that cannot substantially grow crystals from its own surface. An opening is provided, the base substrate is exposed at the bottom in the opening, and the arrangement pattern of the opening on the upper surface of the mask layer is such that the opening is located at the intersection of a mesh having a square as a minimum constituent unit. In the arranged pattern, the square of the minimum structural unit of the mesh is a parallelogram or a square having no sides in the <11-20> direction of the GaN-based crystal grown on the base substrate. A GaN-based crystal growth substrate, characterized in that:

(2) The GaN according to the above (1), wherein the opening has a rectangular shape having two parallel sides extending in the <1-100> direction of a GaN-based crystal grown on a base substrate.
Substrate for crystal growth.

(3) The G according to (1), wherein the parallelogram is a parallelogram having two parallel sides extending in the <1-100> direction of a GaN-based crystal grown on a base substrate.
aN-based crystal growth substrate.

(4) The G according to (1), wherein the parallelogram is a parallelogram having two parallel sides extending in the <11-20> direction of a GaN-based crystal grown on a base substrate.
aN-based crystal growth substrate.

(5) The parallelogram is a parallelogram that does not include a straight line extending in the <1-100> direction and a straight line extending in the <11-20> direction of the GaN-based crystal grown on the base substrate. The GaN-based crystal growth substrate according to the above (1), which is in the form of

(6) The substrate for growing a GaN-based crystal according to any one of the above (1) to (5), wherein the base substrate surface exposed at the bottom in the opening on the substrate is used as a starting point on the mask layer. A method of growing a GaN-based crystal layer until the GaN-based crystal substrate is covered.

The term "parallelogram" as used herein does not include "squares".

Although the crystal orientation of the base substrate itself and the crystal orientation of the GaN-based crystal grown thereon have a unique relationship, they may not completely match. For example, GaN crystals growing on the C-plane of a sapphire crystal substrate are aligned in the C-axis direction, but the a-axis is 30
° The relationship is shifted. Therefore, in this specification, when a specific direction is designated in a plane such as the base substrate surface or the mask layer upper surface by the Miller index (hkil), the GaN grown on the base substrate surface unless otherwise specified. It is indicated by the crystal orientation of the system crystal.

In this specification, if the lattice plane of a hexagonal lattice crystal such as a GaN-based crystal is specified by four Miller indices (hkil), for convenience of description, if the index is negative, it is preceded by the index. The notation is given with a minus sign, and the description method according to the general Miller index is used except for the notation method regarding the negative exponent. Therefore, in the case of a GaN-based crystal, there are six prism surfaces (singular surfaces) parallel to the C axis. For example, one of the surfaces is expressed as (1-100), and the six surfaces are grouped as equivalent surfaces. In that case,
Expressed as 100 °. Also, planes perpendicular to the {1-100} plane and parallel to the C-axis are equivalently grouped into {11-2}.
Notated as 0｝. The direction perpendicular to the (1-100) plane is [1-100], and a set of directions equivalent thereto is <1-1-1.
00>, and the direction perpendicular to the (11-20) plane is [11-
20], and a set of directions equivalent thereto is denoted as <11-20>. However, in the drawings, when the exponent is negative, a minus sign is added to the exponent, and all the notations are followed according to the Miller exponent notation.

In the present specification, a region covered by the mask layer on the base substrate surface is also called a "mask region", and a region exposed on the bottom surface in an opening provided in the mask layer is also called a "non-mask region". explain. The region on the upper surface of the mask layer is regarded as being equal to the mask region, and is used in the description as synonymous.

[0015]

As a countermeasure against cracking of the GaN-based crystal layer caused by the difference between the lattice constant and the coefficient of thermal expansion between the GaN-based crystal and the sapphire crystal substrate, as shown in FIG. On top of this, a mask layer 2 is provided, openings are provided in the mask layer in a matrix pattern (in other words, the mask layers are provided in a grid pattern), and the base substrate surface is exposed in the openings to form a portion. Is a non-mask area, and FIG.
As shown in FIG. 1A, it has been proposed to grow a GaN-based crystal layer 30 only in the non-mask region 11 (Japanese Patent Laid-Open No. Hei.
-273337). By dispersing the chip-size GaN-based crystal layers 30 over the entire surface of the base substrate, the area of each GaN-based crystal layer is reduced, and cracks are prevented.

As a result of further studies by the present inventors, as a result of further growth of the GaN-based crystal layer 30 that is scattered and grown, not only in the thickness direction but also as shown in FIG. It was also confirmed that the growth was also performed in a direction perpendicular to the thickness direction, that is, in a direction extending along the upper surface of the mask layer around the opening (hereinafter, simply referred to as “lateral direction”). In addition, the growth rate was about the same as that in the thickness direction (C-axis direction), and the crystal orientation dependence was found.

Further, Ga in the GaN-based crystal layer 30
The dislocations present in the N-based crystal have the property of being inherited from the base including the base substrate or occurring at any of the growth interfaces and growing together with the crystal growth. As shown in FIG. It has been found that since there is no underlying layer (growth interface) serving as a source in a region corresponding to the region 2 (≒ mask region), a dislocation-free state is obtained. Further, when the above-described lateral growth is further advanced, as shown in FIG. 6C, the GaN-based crystal completely covers the mask layer 2 and embeds the mask layer, and this region has very few defects. It has been found that a large and thick GaN-based crystal layer 3 that is flat and free from cracks can be obtained.

It was also found that the shape of the opening is preferably a shape having sides in the <1-100> direction in the outline. In particular, by forming a rectangular shape having two parallel sides extending in the <1-100> direction, a growth surface of a GaN-based crystal (hereinafter, also simply referred to as “crystal”) that grows laterally from this opening has: The {11-20} plane is secured.
The {11-20} plane is an off-facet plane, and the crystal grows faster than the facet {1-100} plane (M plane). Conversely, a facet plane is a stable plane and crystal growth is slow.

Further, the present inventors, when scattering the openings in the mask layer, change the arrangement pattern of the openings in the <1-100> direction and the <11-20> direction orthogonal to each other as shown in FIG. They found that there was a problem to be solved when they were arranged in a matrix. This will be described below. FIG.
FIG. 8A is a diagram showing a state in which one of the openings in FIG. 7 and its periphery are partially enlarged, and a GaN-based crystal grows laterally from one of the square openings. The opening 4a is G
It is hidden by the aN-based crystal and is indicated by a two-dot chain line. From the side extending in the <1-100> direction among the sides of the opening 4a,
The off-faceted surface 32 grows at high speed in the <11-20> direction, and from the side extending in the <11-20> direction,
The facet 31 grows slowly in the <1-100> direction. For the purpose of explanation, the off-faceted surface is indicated by a thick broken line, and the facetted surface is indicated by a thick line. Immediately after the crystal starts to grow in the lateral direction from the opening, the lateral growth surface is a plane in two directions orthogonal to each other (31, 3 in FIG. 8A).
You may consider only 2). But as growth progresses,
A facet face 33 appears at a corner where the face 31 and the face 32 intersect.

Therefore, the opening is formed as shown in FIG.
As shown in FIG. 8B, when the matrix is arranged in a matrix orthogonal to the -100> direction and the <11-20> direction, the four openings 4a, 4a,
The central region (near the center point m) surrounded by b, 4c and 4d and at an equal distance from each other, is at some point closedly surrounded only by the slow growing facetted surfaces 33a, 33b, 33c and 33d. It will be in a state where it was lost.

Once the facet is surrounded only by such a facet, the following problem occurs. This is the problem to be solved. A. Since it is surrounded only by the facet surface that is slowly growing, it takes a long time to continuously close the surrounded area (space) with the crystal growth. B. When the crystal growth is continued and the enclosed region is closed, the crystal grows at a high speed in the thickness direction (C-axis direction) during that time. It becomes a uselessly long dimension far exceeding the size that has been set. C. Even if the enclosed region is closed, the finally closed portion (center m) is in a state where the growth surfaces from four directions merge at almost one point, so that the crystal quality of the merged portion is:
Those having different crystal orientations are gradually merged, resulting in low crystal quality in which high-density defects including dislocations are concentrated.

In the present invention, the arrangement pattern of the openings is
Avoid a rectangular matrix arrangement orthogonal to the <11-20> direction and the <1-100> direction.
By making the rectangle not include sides in the <20> direction, it is possible to avoid a state where the face is surrounded only by facet faces, and to improve at least one of the above three problems. In particular, FIG.
As shown in the figure, when the growth surface of the crystal gathered from each opening surrounds the central region, two facet surfaces and one
By moving the position of the opening so as to be surrounded by the two off-faceted surfaces, the above three problems are all solved as follows. a. The fast growth of off-faceted surfaces allows the enclosed area to be closed in a short time. b. Since the enclosed region closes early on against growth in the thickness direction, a crystal having an intended thickness can be obtained. c. Since the finally closed portion (center m) has a crystal structure gathered from three directions, the crystal quality is improved as compared with the assembly from four directions. In addition to this, since the enclosed region closes early and then grows in the thickness direction, the crystal quality of the closed portion recovers as it grows in the thickness direction, and at the time when the intended thickness is reached. The crystal quality near the surface has been further improved than at the time of closing.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a GaN-based crystal growth substrate according to the present invention will be described. As shown in FIG. 1, a mask layer 2 is provided on a surface of a base substrate 1 (a mask layer is partially cut away). The mask layer 2 is provided with a plurality of openings 4 from the upper surface, and the base substrate surface is exposed at the bottom in the openings. The arrangement pattern of the openings 4 on the upper surface of the mask layer 2 is such that a mesh having a square S1 (shown by a thick line) as a minimum constituent unit is assumed on the upper surface of the mask layer, and the opening 3 is located at the intersection of the meshes. It is a arranged pattern. In the present invention, the square S1, which is the minimum structural unit of the mesh (hereinafter, simply referred to as "mesh") assumed on the upper surface of the mask layer, is a parallelogram or a side in the <11-20> direction. With no square.

The base substrate may be any substrate on which a GaN-based crystal can be grown. For example, sapphire, crystal, Si
C or the like may be used. Above all, C surface of sapphire, A
A 6H-SiC substrate, particularly a C-plane sapphire substrate, is preferred. In addition, ZnO, Mg for reducing the difference in lattice constant and thermal expansion coefficient with the GaN-based crystal on the surface of these materials.
It may be provided with a buffer layer such as O or AlN.

It is important to select a base substrate having a lattice constant as close as possible and a thermal expansion coefficient as close as possible to the GaN-based crystal to be grown. Is desirable. Further, it is preferable that the mask layer has excellent resistance to high heat and etching when forming a thin film of a mask layer described later. From such a point, the base substrate has at least the surface layer of In _x Ga _y Al _Z N (0 ≦ X ≦ 1, 0 ≦ Y ≦
1, 0 ≦ Z ≦ 1, X + Y + Z = 1). Specifically, on a sapphire substrate, MOVPE
A layer in which a buffer layer of ZnO or AlN or the like and a thin layer of GaN or GaAlN are sequentially formed by the method can be suitably used. With such a base substrate, the density of dislocations newly generated in the GaN-based crystal grown on the base substrate can be suppressed low, and good crystallinity can be obtained.

The mask layer is made of a material that does not allow a GaN-based crystal to grow substantially from its own surface. As such a material, for example, an amorphous body is exemplified, and as the amorphous body, a nitride or an oxide such as Si, Ti, Ta, or Zr is exemplified. In particular, a SiO ₂ film which is excellent in heat resistance and relatively easy to form and remove by etching can be suitably used.

The mask layer is formed, for example, by vacuum deposition, sputtering,
After the substrate is formed so as to cover the entire surface of the substrate by a method such as CVD, the photosensitive resist is patterned by a usual photolithography technique, and a part of the substrate is exposed by etching.

As described above in the description of the operation, the opening shape of the opening is preferably a square having two parallel sides extending in the <1-100> direction. From the two sides extending in the <1-100> direction, since the off-facet surface starts growing at a high speed, it is preferable to secure this side as a long dimension, and conversely, the two sides extending in the <11-20> direction. The shorter the side, the less waste of the substrate surface.

It is not necessary that all of the openings have a congruent shape, and the openings may be varied in size as needed. Conditions for further preferably limiting the opening shape will be described later in connection with the arrangement pattern of the opening.

As described above, the arrangement pattern of the openings is such that the square constituting the minimum structural unit of the mesh is a parallelogram or a square other than the square composed of the <11-20> and <1-100> directions. It is a pattern that is arranged so that
In the embodiment of FIG. 1, the square of the minimum structural unit of the mesh is <1
This is a parallelogram S1 having a part of two parallel straight lines y1 and y2 extending in the −100> direction as two sides. In the figure,
For the sake of explanation, the total number of openings is 9 holes. In the example of FIG. 1, the pattern of the entire mesh assumed on the upper surface of the mask layer is parallel straight lines y1 to y3 extending in the <1-100> direction.
And parallel lines m1 to m3 that intersect these at an angle θ1 (= one of the inner angles of the parallelogram) other than a right angle. The outer peripheral shape of the entire mesh is similar to the parallelogram S1 as the minimum constituent unit in the example of FIG. 3, but, for example, the openings 4e and 4f are omitted. Openings may be added or reduced.

Further, the square of the minimum structural unit of the mesh is
In the case where a parallelogram is required to have two parallel sides extending in the <1-100> direction, such a mesh pattern is determined only by parallel lines in two directions as in the example of FIG. Not only are they all made of congruent parallelograms. For example, as shown in FIG. 2A, a pattern in which parallelograms S1 and S2 mirror-symmetrical to each other are alternately combined, and FIG.
As shown in the figure, a pattern obtained by combining all the parallelograms S11, S12, S21, and S22 as different parallelograms, and a pattern obtained by arbitrarily combining the patterns of FIGS. No.

By setting the arrangement pattern of the openings as shown in FIGS. 1 and 2, the openings 4a, 4b, 4 located at the four vertices of the parallelogram which is the minimum structural unit of the mesh
When the growth surface of the crystals gathered from c and 4d surrounds the central region, the situation where four faces are surrounded only by the facet surface is eliminated. In order to make this feature more pronounced, as shown in FIG. 3, two faceted surfaces 33a,
The shape of a parallelogram, which is the minimum structural unit of the mesh, so as to be in a state surrounded by 33c and one off-facet surface 32d (there is also a state surrounded by surfaces 33b, 33d, and 32a at this time). It is preferable to determine the shape of the opening and the shape of the opening as follows.

When the opening shape is a rectangle having a long side in the <1-100> direction, the length of the long side is, as described with reference to FIG. 3, the facet face 33a from the two openings 4a and 4c. When the contact with the surface 33c, the off-facetted surface 32d corresponds to these surfaces 33a and 33c and can form a triangle. Is preferred. Illustrative dimensions of the opening shape are, for example, 10 μm to 10 mm in the <1-100> direction, and 1 μm to 10 mm in the <11-20> direction.
It is preferable to select from the range of μm such that the rectangle is long in the <1-100> direction.

Regarding the shape of the parallelogram which is the minimum structural unit of the mesh, one of the two sides in the <1-100> direction is set to <1-10
A shape shifted in the 0> direction is preferable. In other words, in the case of FIG. 1, the openings 4 located at the four vertices of the parallelogram are
a, 4b, 4c, and 4d, a set of three openings (4
a, 4c, 4d) and (4a, 4d, 4b) are each 2
The shape is a parallelogram located at the apex of an equilateral triangle. The length of the side of the parallelogram in the <1-100> direction is
It is determined from the dimensions of the opening shape and the gap (length of the mask region) between the openings in the <1-100> direction. <1-
The gap between the openings in the <100> direction is about 1 μm to 10 μm, whereas the crystal grows at a high speed <11−
The gap between the openings in the <20> direction is about 2 μm to 50 μm. These dimensions may be determined with reference to the crystal growth rate in the lateral direction.

Next, another embodiment of the arrangement pattern of the openings will be described. The mode shown in FIG. 4 is a mode in which the square as the minimum structural unit of the mesh is a parallelogram S3 having two parallel sides extending in the <11-20> direction. By adopting the mode shown in the figure, when the crystal is grown in the lateral direction, it is in a state surrounded by only the facet surface (region indicated by hatching), and this region cannot be closed early, As compared with the mode of merging from four directions shown in FIG. 8B, as described in the above description of the operation, the finally closed portion has a crystal structure merging from three directions, so that the crystal quality is low. Be improved.

In the embodiment shown in FIG. 5, the square of the minimum structural unit of the mesh is formed by a straight line extending in the <1-100> direction and a <1-100> line.
In this embodiment, none of the straight lines extending in the <1-20> direction is a parallelogram. In addition, a mode in which the square of the minimum structural unit of the mesh is a square that does not include any of the straight lines extending in the <1-100> direction and the straight lines extending in the <11-20> direction on the sides also has the same effect as in FIG. 5. Is the same. By adopting such an aspect, the shape when the lateral growth surface surrounds the central region becomes complicated, but due to the presence of the off-facet surface, this region is closed early, and the structure shown in FIG. Similarly, the crystal quality of the last closing part can be improved.

The method for producing a GaN-based crystal substrate according to the present invention comprises:
This is a manufacturing method for growing a GaN-based crystal using the GaN-based crystal growth substrate described above. The growth of the GaN-based crystal starts from a non-mask portion (the bottom surface of the opening) on the base substrate as a starting point. As the growth continues, the inside of the opening is filled with a GaN-based crystal as shown in FIG. 6A, and the GaN-based crystal swells higher than the upper surface of the mask layer as shown in FIG. 6B. . At this time, the GaN-based crystal starts growing not only in the height direction (C-axis direction) but also in the lateral direction starting from the side surface of the bulging portion. The growth in the lateral direction is as shown in FIGS. Eventually, the region surrounded by the lateral growth surface is closed, and FIG.
As shown in (c), the mask layer 2 is completely covered and the growth in the thickness direction is continued to form a GaN-based crystal layer. This GaN-based crystal layer alone is cut out or used as a GaN-based crystal substrate while being integrated with the base substrate.

In the GaN-based crystal layer formed on the GaN-based crystal growth substrate according to the present invention, as shown in FIG. 6 (c), a portion corresponding to a portion immediately above the non-mask portion is inherited by defects such as dislocations. Sometimes. However, at least the mask layer 2
Since the upper portion is formed by lateral growth starting from the side surface of the bulge (the surface having no defects such as dislocations) as a starting point, an extremely high-quality crystal having no defects such as dislocations is formed. It is. In addition, the direct contact portion between the GaN-based crystal layer and the base substrate is only the non-mask portion, the contact area is small, and the GaN-based crystal layer is not largely affected by the difference in the thermal expansion coefficient between the two, so that a thick GaN-based crystal layer is easily formed. There is also the advantage that it can be grown in

The GaN-based crystal to be grown on the GaN-based crystal growth substrate of the present invention has the formula In _x Ga _Y Al _Z
N (0 ≦ X ≦ 1, 0 ≦ Y ≦ 1, 0 ≦ Z ≦ 1, X + Y + Z
= 1). In particular, GaN is useful as a thick film layer.

The method of growing the GaN-based crystal is not limited, and examples thereof include HVPE, MOVPE, and MBE. Among them, HVPE is particularly preferable because it has an advantage that the growth rate is very high.

GaN obtained by the manufacturing method of the present invention
A light-emitting element such as an LED or an LD can be manufactured by using a base crystal substrate or a GaN-based semiconductor substrate and forming a light-emitting portion and an electrode including a cladding layer and an active layer on the substrate.

[0042]

【Example】

Embodiment 1 In this embodiment, as shown in FIG. 1, the square of the minimum structural unit of the mesh in the arrangement pattern of the openings is changed to <1-10
A GaN-based crystal growth substrate was manufactured as a parallelogram having two parallel sides extending in the 0> direction, and a GaN crystal substrate was manufactured using the substrate.

[Manufacture of GaN Crystal Growth Substrate] Diameter 2
Inch, 330 μm thick, C-plane sapphire substrate
Using an OVPE apparatus, an AlN buffer layer having a thickness of 20 nm was grown at a low temperature, and then a GaN thin layer having a thickness of 1.5 μm was grown and used as a base substrate. After a mask layer made of a SiO ₂ thin film was formed on the entire surface of the substrate by a sputtering method, an opening was provided by etching to obtain a GaN-based crystal growth substrate of the type shown in FIG.

The shapes of the openings are all the same,
3 μm in <11-20> direction × 100 in <1-100> direction
It is a rectangle of μm.

The arrangement pattern of the openings is the distance between the openings adjacent to each other (the width of the mask area sandwiched between the openings).
Is 5 μm in the <11-20> direction and 2 in the <1-100> direction.
μm, one of the two sides in the <1-100> direction in the parallelogram of the minimum structural unit of the mesh is one-half the length of the side in the <1-100> direction with respect to the other. It is a parallelogram pattern shifted.

[Formation of GaN-based Crystal Layer] The above-mentioned GaN-based crystal growth substrate was loaded into an HVPE apparatus, and as shown in FIG. 6, a 200 μm-thick Ga
An N-based crystal layer was formed. The GaN-based crystal grew also on the mask layer in the lateral direction and completely covered the mask layer.

The flatness on the GaN-based crystal layer was good. The portion where the crystals grew in the lateral direction from each opening and merged was a merge from three directions to one point, grew in the thickness direction after the merge, and the crystal quality near the surface layer was good. .

[0048]

As described above, the present invention relates to GaN
Due to the characteristics of the arrangement pattern of the openings in the substrate for system crystal growth, crystals grown in the lateral direction from the respective openings are earlier than the orthogonal matrix arrangement patterns in the <11-20> direction and the <1-100> direction. It is possible to close the confluence point, and the crystal quality can be improved by subsequent growth in the thickness direction. In addition, the number of laterally growing surfaces converging at the junction can be reduced from four to three, and from this point the crystal quality is also improved.

[Brief description of the drawings]

FIG. 1 is a view showing one example of a GaN-based crystal growth substrate of the present invention, and is a view showing an arrangement pattern of openings on a mask layer.

FIG. 2 is a diagram showing a variation of an arrangement pattern of openings shown in FIG. 1; Only the arrangement pattern is extracted from the substrate and shown. The crystal orientation on the paper surface of FIG. 2B is the same as in FIG.
20>.

FIG. 3 is a diagram showing an operation by the arrangement pattern of FIG. 1 or FIG. 2;

FIG. 4 is a view showing another example of the arrangement pattern of the openings in the substrate for growing a GaN-based crystal of the present invention.
This shows a state in which the lateral growth surface of the crystal grown from each opening surrounds the central region. The enclosed area is hatched.

FIG. 5 is a view showing another example of the GaN-based crystal growth substrate of the present invention.

FIG. 6 is a diagram showing how a GaN-based crystal layer grows on a mask layer in a lateral direction.

FIG. 7 is a diagram showing an example in which the arrangement pattern of openings is an orthogonal matrix arrangement pattern composed of <1-100> directions and <11-20> directions. In this figure, the base substrate 1 is shown with the mask layer 2 partially cut away and cut away. The upper surface of the mask layer is hatched, and the base substrate surface appears on the inner bottom surface of each opening 4.

FIG. 8 is a view showing a state in which a crystal grows laterally from an opening. In particular, in FIG.
It shows a state where it joins one point from the direction. FIG. 8B
The crystal orientation on the paper surface is the same as in FIG.
100> and left and right <11-20>.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base substrate 2 Mask layer 4 Opening S1 Square of minimum structural unit of mesh

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoichiro Ouchi 4-3 Ikejiri, Itami-shi, Hyogo Mitsubishi Electric Cable Industry Co., Ltd. Itami Works

Claims (6)

[Claims] 1. A mask layer is provided on a surface of a base substrate on which a GaN-based crystal can be grown. The mask layer is made of a material that cannot substantially grow crystals from its own surface. A plurality of openings are provided, the base substrate is exposed at the bottom in the openings, and the arrangement pattern of the openings on the top surface of the mask layer is such that the openings are located at the intersections of the meshes having a square as a minimum constituent unit. And the square of the smallest structural unit of the mesh is a parallelogram or does not have a side in the <11-20> direction of the GaN-based crystal grown on the base substrate. A GaN-based crystal growth substrate having a rectangular shape. 2. The substrate for growing a GaN-based crystal according to claim 1, wherein the opening has a rectangular shape having two parallel sides extending in a <1-100> direction of the GaN-based crystal grown on the base substrate. . 3. The GaN-based crystal for growing a GaN-based crystal according to claim 1, wherein the parallelogram is a parallelogram having two parallel sides extending in a <1-100> direction of a GaN-based crystal grown on a base substrate. substrate. 4. The GaN-based crystal for growing a GaN-based crystal according to claim 1, wherein the parallelogram is a parallelogram having two parallel sides extending in the <11-20> direction of a GaN-based crystal grown on a base substrate. substrate. 5. A parallelogram which does not include any of a straight line extending in the <1-100> direction and a straight line extending in the <11-20> direction of the GaN-based crystal grown on the base substrate. The GaN-based crystal growth substrate according to claim 1, wherein 6. The GaN according to claim 1,
A step of growing a GaN-based crystal layer from a base substrate surface exposed at a bottom in an opening on the substrate using a substrate for growing the base crystal to cover a mask layer from the starting point. Substrate manufacturing method.