JP2001156002A - Semiconductor base material and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid various problems caused by ELO growth using ordinary mask layers and, in addition, to simplify the manufacturing process of a semiconductor base material. SOLUTION: In this method of manufacturing a semiconductor base material, a substrate 1 having a growing surface made on an uneven surface and masks 3 formed on the recessed surface 12 of the growing surface as shown in Fig. (a) is used. When vapor growth is made by using the substrate 1, crystal growth occurs only from the tops of the projecting sections 11 of the growing surface due to the masks 3. At starting the crystal growth, therefore, crystal units 20 only occur as shown in Fig. (b), when the crystal growth is continued, films grown in the lateral direction from the tops of the projecting section 11 are joined together, and finally, cover the uneven surface of the substrate 1 by leaving cavity sections 13 as they are, in the recessed sections 12 as shown in Fig. (c). In this case, low dislocation areas are formed in the laterally grown sections, namely, above the recessed sections 12, and the quality of the formed film is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate and a method for manufacturing the same, and more particularly to a structure and a method useful when a semiconductor material in which dislocation defects easily occur is used.

[0002]

2. Description of the Related Art When a GaN-based material is crystal-grown, Ga
N-type materials have no lattice-matched substrate, so sapphire,
A substrate that does not lattice match, such as SiC, spinel, or recently Si, is used. However, as many as 10 ¹⁰ dislocations / cm ² exist in the GaN film produced due to lack of lattice matching. In recent years, high brightness light emitting diodes,
Although a semiconductor laser or the like has been realized, a reduction in dislocation density is desired to improve characteristics.

[0003]

As a method for reducing the dislocation density, for example, a GaN-based semiconductor crystal or the like is grown on a sapphire substrate by growing a buffer layer and a GaN layer on a sapphire substrate, and using the GaN layer as an undersubstrate. A method has been proposed in which a crystal is grown in the lateral direction by providing a selective mask and performing selective growth to obtain a high-quality crystal with reduced dislocation density (for example, JP-A-10-312971).

However, according to the above-mentioned method, a problem arises in that the c-axis is tilted in the lateral growth direction with a small amount in the laterally grown portion on the mask layer, thereby deteriorating the crystal quality. It turned out to be a problem (MSR 1998 Fall, Meeti
ng Proceedings G3.1). This measures the incident azimuth dependence of X-ray rocking curve measurement (XRC) (¢ scan)
You can also confirm by doing. That is, the full width at half maximum (F) of the X-ray rocking curve due to the incident X-rays from the lateral growth direction.
WHM) is larger than the FWHM value of the mask layer by X-rays from the stripe direction, indicating that the slight tilt (tilting) of the C-axis has an orientation dependency.
This suggests that many new defects may be induced in the merged portion of the lateral growth on the mask.

As an attempt to solve such a problem, S
A substrate provided with a buffer layer and a GaN layer on an iC base substrate is subjected to stripe groove processing up to the SiC layer to form a convex portion, and the GaN layer located above the convex portion (MRS 1998 Fall Meeting Proceedings G3.38) has been proposed.
According to this method, selective growth can be performed without the SiO ² mask layer, and various problems caused by using the above-described SiO ² mask can be solved.

In the above method, a sapphire substrate can be used as a base substrate, and a method thereof is also disclosed (for example, JP-A-11-191659). However, the above-described method requires a step of growing a buffer layer material and a GaN-based material on a sapphire base substrate, crystallizing the buffer layer once, removing the groove from the growth furnace, and then performing crystal growth again. There has been a problem that new inconvenience such as complication occurs, the number of work steps increases, and the cost increases.

[0007] (Applied Physics Society 99 Autumn Proceedings 2P-W
-8) also discloses an attempt to obtain a low dislocation density region by growing a GaN substrate with a step and performing burying growth. Here, a low dislocation density region is formed in a part of the buried layer. However, in the above method, in order to obtain a low dislocation density region, it is necessary to increase the interval between the convex portions or to increase the depth of the concave portions. In order to achieve this, it is necessary to take a long time to bury the film and to grow it thickly, and there are various problems such as the occurrence of cracks due to the thickening of the film and the cost of taking time.

Attempts have also been made to grow a GaN-based material on a Si substrate. However, when a GaN-based crystal is grown, warpage and cracks are generated due to a difference in thermal expansion coefficient, so that a high-quality crystal cannot be grown. there were.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to avoid various problems caused by ELO growth using a normal mask layer and to simplify the manufacturing process. It is another object of the present invention to solve the problem caused by the buried growth of the step structure having no mask. Furthermore, Si
It is intended to suppress the occurrence of warpage and cracks when using a substrate or the like.

[0010]

The semiconductor substrate of the present invention comprises:
A semiconductor substrate comprising a substrate and a semiconductor crystal vapor-grown on the substrate, wherein the crystal growth surface of the substrate is an uneven surface, and the concave portion is substantially incapable of crystal growth from the layer. And the semiconductor crystal is formed by crystal growth exclusively from the upper part of the projection on the uneven surface. In this case, the semiconductor crystal is InG
aAlN is desirable.

It is preferable that the projection on the crystal growth surface of the substrate is a projection having a parallel stripe shape. Further, the semiconductor crystal is InGaAlN, and the longitudinal direction of the stripe is (1-1) of the InGaAlN crystal.
More preferably, the stripe is perpendicular to the (00) plane.

A more specific semiconductor substrate according to the present invention is a semiconductor substrate comprising a substrate and a semiconductor crystal grown by vapor deposition on the substrate, wherein the crystal growth surface of the substrate has an uneven surface. The concave portion is covered with a mask that cannot substantially grow crystals from the layer, and the semiconductor crystal is grown on the semiconductor substrate exclusively crystal-grown from above the convex portion on the concave-convex surface. And a cavity portion is formed between the semiconductor crystal layer and the concave portion on the uneven surface.

Further, the semiconductor base material has an uneven surface on the crystal growth surface of the substrate, the concave portion is covered with a mask that cannot substantially grow crystals from the layer, and the convex portion on the uneven surface is formed by a vapor phase growth method. A first semiconductor crystal formed by exclusively growing a crystal from the upper part of the first semiconductor crystal, and the surface of the first semiconductor crystal has an uneven surface, and similarly, a concave portion cannot be substantially grown from the layer. A configuration including a second semiconductor crystal formed by covering with a mask and exclusively performing crystal growth from above the convex portion may be employed.

Further, the surface of the second semiconductor crystal in the semiconductor substrate is made uneven, and the recess is covered with a mask that cannot substantially grow crystals from the layer. A plurality of semiconductor layers formed in a multiplexed manner by repeating the formed third semiconductor layer or similar steps may be provided.

According to the method of manufacturing a semiconductor substrate of the present invention, when a semiconductor crystal is vapor-phase grown on a substrate, the surface of the substrate is subjected to a roughening process in advance, and the concave portion on the rough surface is substantially crystallized from the layer. Covering with a mask that cannot grow, then supplying a source gas to the substrate, and covering the uneven surface of the substrate with a semiconductor crystal that is exclusively crystal-grown from above the convex portion in the uneven surface. I do.

[0016]

According to the present invention, an uneven surface is provided on a substrate in which even a buffer layer or the like is not formed, and the concave portion is covered with a mask which cannot substantially grow from the layer, so that the substrate can be substantially grown from the beginning of crystal growth. It is characterized in that a substrate for lateral growth capable of forming a low dislocation density region is provided in advance.
That is, in the case of vapor phase growth, the raw material diffuses over the entire substrate surface in the initial stage of growth, but since crystal growth is unlikely to occur on the concave mask, the growth in the convex portion becomes dominant, and thus the layer grown from the convex portion. It is covered with.

In the growth of the projections, so-called lateral growth in the direction perpendicular to the C axis occurs, and a low dislocation density region is formed. Thus, the growth of the crystal base material having the low dislocation density region can be performed only once, and the subsequent growth process can be performed continuously. In addition, since growth in the concave portion can be suppressed, the efficiency of lateral growth is improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. 1A to 1C are cross-sectional views for explaining a crystal growth state of a semiconductor substrate according to the present invention. In the drawing, reference numeral 1 denotes a substrate, and 2 denotes a semiconductor crystal grown on the substrate 1 by vapor phase. A convex portion 11 and a concave portion 12 are formed on the crystal growth surface of the substrate 1, and the crystal growth is performed exclusively from above the convex portion 11. The recess 12 is covered with a mask 3 that cannot substantially grow from the layer.

The substrate referred to in the present invention is a substrate serving as a base for growing various semiconductor crystal layers, in which a buffer layer or the like for lattice matching has not been formed yet. Such substrates include sapphire (C plane, A plane, R plane), SiC (6H, 4H, 3C),
GaN, Si, spinel, ZnO, GaAs, NGO, and the like can be used, but other materials may be used as long as they correspond to the object of the invention. In addition, those off from these substrates may be used.

Various semiconductor materials can be used for the semiconductor crystal grown on the substrate 1, and Al _x Ga _1-xy
In In _y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1), GaN, Al _0.5 Ga _0.05 N, and In _0.5 G in which the composition ratio of x and y is changed
a _0.05 N and the like.

Convex portion 11 formed on the crystal growth surface of substrate 1
It is effective to make the shape such that crystal growth is performed exclusively from above. The phrase “crystal growth is performed exclusively from the upper part” refers to a state in which crystal growth can be predominantly performed at the apex or top surface of the convex part 11 and in the vicinity thereof. Good, but ultimately indicates that the crystal growth of the convex portion 11 becomes dominant.

The mask 3 formed on the recess 12 is
It suffices if the layer does not substantially grow crystals. The phrase "can not substantially grow from that layer" means a state in which crystal growth is unlikely to occur. In the initial stage of growth, growth on the concave mask may occur. Refers to the predominance of crystal growth. That is, if a low dislocation density region is formed by lateral growth starting from the upper part, the same effect as that of the conventional ELO requiring a mask can be obtained. This is a feature of the present invention in that a low dislocation density region can be formed by a single crystal growth only by processing the substrate. Hereinafter, this point will be described with reference to FIGS.

FIG. 1 and FIG. 2 are cross-sectional views of a projection formed in a stripe shape. First, FIG. 1 illustrates a case where a substrate 1 having a groove depth (height of a convex portion) h larger than a groove width B as shown in FIG. In this case, the source gas does not sufficiently reach the concave portion 12 and its vicinity, and since the concave portion 12 is covered with the mask 3, crystal growth occurs only from above the convex portion 11. In FIG. 1B, 20
Indicates the crystal unit at the start of the crystal growth. Under such circumstances, when the crystal growth continues, the films grown in the lateral direction starting from the upper part of the convex portion 11 are connected, and the film shown in FIG.
As described above, the concave / convex surface of the substrate 1 is covered with the cavity 13 left in the concave. In this case, a low dislocation region is formed in the portion grown in the lateral direction, that is, in the upper part of the concave portion 12, thereby improving the quality of the formed film.

FIG. 2 shows groove depth (groove height) with respect to groove width B.
The case where h is very shallow, or the case where the substrate 1 whose groove width B is very large with respect to the width A of the convex portion 11 is used (see FIG. 2A). In this case, since the source gas can reach the mask 3 in the concave portion 12 and its vicinity, the growth in the concave portion 12 may occur. However, the growth rate is much slower than the growth at the upper part of the protrusion. This is because the rate at which the raw material reaching the mask 3 is desorbed again into the gas is large. As a result, crystal growth in the lateral direction occurs from the upper part of the convex part 11, and as shown in FIG. 2B, a crystal unit 20 is generated on the upper part of the convex part 11 and on the surface of the concave part 12. . Under such circumstances, when the crystal growth continues, the films grown in the lateral direction starting from the upper part of the convex portion 11 are connected, and the film shown in FIG.
As shown in (c), the uneven surface of the substrate 1 is covered. In this case, the portion grown in the lateral direction starting from the convex portion 11 is larger than in the example of FIG. 1, so that the ratio of the low dislocation region is large, and the quality of the formed film is higher than that of FIG. Will be achieved.

In the present invention, there is no particular limitation as long as such a convex portion 11 is used, and various shapes can be adopted. Specifically, when the groove depth (projection height) h is larger than the groove width B as described above, when the groove depth (projection height) h is smaller than the groove width B, the groove width is further increased. Various combinations can be performed, such as when the groove depth (height of the convex portion) h is very shallow with respect to B, or when the groove width B is very large with respect to the width A of the convex portion 11. In particular, it is preferable that the groove width B is wider than the width A of the convex portion 11 because a portion grown in the lateral direction starting from the upper portion of the convex portion 11 increases and a low dislocation region is formed widely.

As a mode of forming such an uneven surface,
Examples include island-shaped dotted projections, stripe-shaped projections, lattice-shaped projections, and projections in which the lines forming these are curved. Among these projections, the one in which the stripe-shaped projections are provided is preferable because the manufacturing process can be simplified and a regular pattern can be easily manufactured. The longitudinal direction of the stripe may be arbitrary, but when the material to be grown on the substrate is GaN,
The <11-20> direction and the <1-100> direction of the GaN-based material are preferable. In particular, in the case of <1-100> direction,
Since the oblique facet such as the {1-101} plane is hardly formed, the lateral growth (lateral growth) is accelerated. As a result, it is particularly preferable that the uneven surface is quickly covered.

As the mask 3 formed on the concave portion 12,
It is sufficient that the layer does not substantially grow from that layer, and SiO ₂ , SiNx, TiO ₂ , ZrO _{2 and the} like can be used. It is also possible to adopt a laminated structure of these materials.

As in the embodiment shown in FIG. 1, when the light-emitting element is manufactured by filling the uneven portion of the substrate 1 while leaving the hollow portion 13 and then growing the light-emitting portion thereon, the hollow portion and the semiconductor A large difference in the refractive index at the interface can be obtained. As a result, the rate at which light directed downward from the light emitting portion is reflected at this interface increases.
For example, when the LED is die-bonded with the sapphire substrate surface facing downward, it is preferable because the amount of light that can be extracted upward increases.

Further, burying the cavity 13 while leaving it intact means that the contact area between the substrate 1 and the semiconductor layer grown thereon can be reduced, so that the difference between the lattice constant and the coefficient of thermal expansion in the semiconductor is reduced. This is preferable in that the resulting distortion can be reduced. This reduction in strain has the effect of reducing the warpage that occurs when a GaN-based material is grown thick on sapphire.
In particular, in the conventional method, when a GaN-based material is crystal-grown on a Si substrate, there is a problem that warpage and cracks are generated due to a difference in thermal expansion coefficient, so that high-quality crystal growth cannot be performed. Eliminate problems.

Further, taking advantage of the fact that the contact area between the substrate 1 and the semiconductor layer 2 grown thereon can be reduced, when the semiconductor layer 2 grows thick, stress concentrates on this small contact portion. The substrate 1 and the semiconductor layer 2 can be separated from the portion. By applying this, a substrate such as GaN can be manufactured.

Although the case where only one semiconductor layer 2 is grown on the substrate 1 has been described above, the same process may be repeated twice to reduce dislocation defects. That is, as shown in FIG. 4, after the crystal growth of the first semiconductor layer 2a is performed to cover the uneven surface of the substrate 1 by the same method as described above, the surface of the first semiconductor layer 2a is A second semiconductor crystal 2b can be formed by providing a mask 3a so that the surface is processed and a crystal is exclusively grown on the surface of the first semiconductor layer 2a from above the convex portion 11a by vapor phase growth. . In this case, if the position of the protrusion 11 of the substrate 1 and the position of the protrusion 11a formed on the first semiconductor layer 2a are shifted in the vertical direction, the second semiconductor layer 2
Many dislocations above the protrusions 11a of the first semiconductor layer 2a do not propagate to b. That is, with such a configuration, the entire region of the second semiconductor layer 2b can be a low dislocation region, and a higher quality semiconductor layer can be obtained.

Further, the surface of the second semiconductor crystal 2b may be made more uneven, and a third semiconductor layer similarly formed by vapor deposition may be formed thereon. Alternatively, a similar process may be repeated to form a plurality of semiconductor layers in a multiplex manner. With such a configuration, dislocations that propagate each time a layer is stacked can be gradually reduced without intentionally adjusting the position of the upper and lower convex portions as described above.

The projections are formed by patterning according to the shape of the projections using, for example, ordinary photolithography technology.
It can be manufactured by performing an etching process using an IE technique or the like.

As a method for growing a crystal of a semiconductor layer on a substrate, HVPE, MOCVD, MBE or the like is preferable. When forming a thick film, the HVPE method is preferable, but when forming a thin film, the MOCVD method is preferable.

The growth conditions (gas type, growth pressure, growth temperature, etc.) for growing a semiconductor layer on a substrate may be properly selected depending on the purpose as long as the effects of the present invention can be obtained. .

[0036]

[Example 1] Photoresist patterning (width: 2 µm, period: 6 µm, stripe orientation: stripe extending direction is <11-20> direction of sapphire substrate) on c-plane sapphire substrate, and RIE ( Reactive Ion E
Etching was performed in a rectangular cross section to a depth of 2 μm using a tching apparatus. Subsequently, a 0.1 μm SiO ₂ film was deposited on the entire surface of the substrate, and then the photoresist and the SiO ₂ film deposited thereon were removed by a lift-off process. Thus, the mask layer was applied to the concave portions of the substrate. Then, the substrate was mounted on the MOVPE device, and the temperature was raised to 1100 ° C. in a hydrogen atmosphere.
Thermal etching was performed. Thereafter, the temperature was lowered to 500 ° C., and trimethylgallium (hereinafter referred to as TM) was used as a Group 3 raw material.
G) was fed with ammonia as an N source to grow a GaN low temperature buffer layer. Subsequently, the temperature was raised to 1000 ° C., and TMG / ammonia was flowed as a raw material, and silane was flowed as a dopant to grow an n-type GaN layer on the substrate. The growth time at that time is the same as that of Ga
A time corresponding to 4 μm in N growth was set.

Observation of the cross section after growth reveals some traces of growth on the substrate concave mask, but as shown in FIG. 2C, the concave and convex portions are covered while leaving the hollow portions 13 in the concave portions, and are flattened. The resulting GaN film was obtained.

For comparison, a GaN layer formed on a normal c-plane sapphire substrate under the same growth conditions and a GaN film grown by ELO using an SiO ₂ mask having the same pattern were prepared. The evaluation was performed using InGaN (InN mixed crystal ratio = 0.2, 10
The pits (corresponding to dislocations) appearing as they continue to grow (thickness of 0 nm) were counted and defined as dislocation densities. Table 1 shows the evaluation results.

[0039]

[Table 1]

It can be seen that in the sample of the embodiment, the dislocation density can be reduced to about the same level as in the conventional ELO. Further, the FWHM of XRC is 170 seconds, which is the smallest, and can be said to be a high quality film as a whole.

Example 2 An n-type AlGaN cladding layer, an InGaN light emitting layer, and a p-type layer were continuously formed on the film obtained in Example 1.
An AlGaN cladding layer and a p-type GaN contact layer were sequentially formed to produce an ultraviolet LED wafer having an emission wavelength of 370 nm. Thereafter, electrode formation and element isolation were performed to obtain an LED element. The average value of the output of the LED chips collected over the entire wafer and the reverse current characteristics were evaluated. For comparison, an ultraviolet LED chip with the above structure fabricated using conventional ELO technology and an ultraviolet LED with the above structure fabricated using a normal sapphire substrate
LED chip. Table 2 shows the evaluation results.

[0042]

[Table 2]

As shown in Table 2, it was found that the sample manufactured using the present invention has a higher output and a higher quality LED with less leak current than the conventional example.

Embodiment 3 Next, an example using GaN as a substrate will be described. Patterning of photoresist on GaN substrate (width: 2 μm, period: 6 μm, stripe orientation: G
aN substrate <1-100>) and RIE (Reactive Ion Et
ching) The device was etched in a square cross section to a depth of 2 μm. Subsequently, a SiO ₂ film was deposited to a thickness of 0.1 μm on the entire surface of the substrate, and then the photoresist and the SiO ₂ film deposited thereon were removed by a lift-off process. The GaN substrate thus processed is mounted on a MOVPE apparatus, and nitrogen,
The temperature was raised to 1000 ° C. in a mixed atmosphere of hydrogen and ammonia. Thereafter, TMG / ammonia was flowed as a raw material and silane was flowed as a dopant to grow an n-type GaN layer. The growth time at that time is the normal GaN
A time corresponding to 4 μm in growth was set.

Observation of the cross-section after growth reveals some traces of growth on the concave mask of the substrate, and growth on the side surfaces of the convex portion. However, as shown in FIG. Was obtained. Subsequently, the pits of the obtained film were evaluated. GaN used as substrate
The pit density was 2 × 10 ⁵ cm ⁻³ , but when the growth of this example was performed, the pits decreased to 1 × 10 ⁵ cm ^{−3 at} the upper part of the convex part and to 5 × 10 ³ cm ⁻³ at the upper part of the concave part. I knew I was doing it. Thus, it was confirmed that even a substrate having a small number of dislocations has a further effect of reducing the dislocation density.

Example 4 The GaN crystal produced in Example 1 was used as a first crystal, on which a second crystal was grown. First, a photoresist is patterned on the first GaN crystal (width: 2 μm, period: 6 μm, stripe orientation: GaN
The substrate was subjected to <1-100>) and etched in a square cross section to a depth of 2 μm by RIE. At this time, the patterning was performed so that the concave portion of the first crystal came on the convex portion of the substrate. Subsequently, a SiO ₂ film was deposited to a thickness of 0.1 μm on the entire surface of the substrate, and then the photoresist and the SiO ₂ film deposited thereon were removed by a lift-off process. After such processing, the substrate was mounted on a MOVPE apparatus, and the temperature was raised to 1000 ° C. in a mixed atmosphere of nitrogen, hydrogen and ammonia. Thereafter, TMG-ammonia was flowed as a raw material and silane was flowed as a dopant to grow an n-type GaN layer. The growth time at that time was set to a time corresponding to 4 μm in the GaN growth in the case where the normal unevenness was not applied.

Observation of the cross section after growth reveals some traces of growth on the concave mask of the substrate and growth on the side surfaces of the convex portion. However, as shown in FIG. Was obtained. Subsequently, when the pits of the obtained film were evaluated, it was found that the pits were reduced to 8 × 10 ⁵ cm ⁻³ . As described above, it was confirmed that the effect of reducing the dislocation density was further obtained by repeating this example.

[0048]

According to the semiconductor substrate and the method of manufacturing the same according to the present invention as described above, a projection is provided on a substrate,
By covering the recess with a mask that cannot substantially grow from the layer, lateral growth that can form a substantially low dislocation density region can be preferentially performed from the beginning of crystal growth. Therefore, it is possible to solve the problem of the generation of new defects in the united portion of the laterally grown portion due to the minute tilting of the axis, and the problem of autodoping, which are problems caused by the ELO growth for forming the normal mask layer. In addition, by simply performing the above-described processing on the substrate, the growth of the buffer layer and the growth of the semiconductor crystal layer such as the light emitting portion can be continuously performed in a single growth, so that there is an advantage that the manufacturing process can be simplified. In particular, since the growth in the concave portion can be suppressed, there is an advantage that the efficiency of lateral growth is improved. Further, the use of the hollow portion has an effect of improving the reflectance and suppressing residual strain, and is a very valuable invention in terms of improving characteristics and reducing costs.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a crystal growth state of a semiconductor substrate according to the present invention.

FIG. 2 is a cross-sectional view for explaining a crystal growth state of a semiconductor substrate according to the present invention.

FIG. 3 is a cross-sectional view for explaining a crystal growth state of a semiconductor substrate according to the present invention.

FIG. 4 is a cross-sectional view illustrating a crystal growth state of a semiconductor substrate according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 11 Convex part 12 Concavity 13 Cavity part 2 Semiconductor layer 3 Mask

Continued on the front page (72) Inventor Masahiro Koto 4-3 Ikejiri, Itami-shi, Hyogo Mitsubishi Electric Cable Industry Co., Ltd. Itami Works F-term (reference) 4G077 AA03 BE11 DB01 ED04 ED05 EE07 5F045 AA04 AA05 AB14 AB17 AB18 AC01 AC08 AC12 AC15 AC19 AD14 AF02 AF04 AF09 AF12 CA11 DB02 DB04

Claims (8)

[Claims] 1. A semiconductor substrate comprising a substrate and a semiconductor crystal grown on the substrate by vapor phase growth, wherein the crystal growth surface of the substrate is an uneven surface, and the concave portion is substantially crystallized from the layer. A semiconductor substrate covered with a mask that cannot grow, wherein the semiconductor crystal is grown exclusively from a portion above the convex portion on the uneven surface. 2. The semiconductor substrate according to claim 1, wherein said semiconductor crystal is InGaAlN. 3. The semiconductor substrate according to claim 1, wherein the projection on the crystal growth surface of the substrate is a projection having a parallel stripe shape. 4. The semiconductor substrate according to claim 3, wherein the semiconductor crystal is InGaAlN, and a longitudinal direction of the stripe is perpendicular to a (1-100) plane of the InGaAlN crystal. 5. A semiconductor substrate comprising a substrate and a semiconductor crystal vapor-grown on the substrate, wherein the crystal growth surface of the substrate is an uneven surface, and the concave portion is substantially crystallized from the layer. The semiconductor crystal is covered with a mask that cannot grow, and the semiconductor crystal is covered with the semiconductor crystal on which the uneven surface is grown, in a semiconductor substrate that is exclusively crystal-grown from above the convex portion on the uneven surface. The semiconductor substrate according to claim 1, wherein a cavity is formed between the crystal layer and the concave portion on the uneven surface. 6. A crystal growth surface of a substrate is formed as an uneven surface, and a concave portion is covered with a mask which cannot substantially grow a crystal from the layer,
A first semiconductor crystal formed by exclusively growing a crystal from the upper portion of the convex portion in the concave-convex surface by a vapor phase growth method, and the surface of the first semiconductor crystal is a concave-convex surface, and the concave portion is similarly formed. A semiconductor substrate comprising a second semiconductor crystal formed by covering a layer with a mask that cannot substantially grow crystals, and performing crystal growth exclusively from above the convex portions. 7. The semiconductor substrate according to claim 6, wherein the surface of the second semiconductor crystal is an uneven surface, and the concave portion is covered with a mask that cannot substantially grow crystals from the layer. A semiconductor substrate having a third semiconductor layer formed by a growth method or a plurality of semiconductor layers formed in a multiplex manner by repeating similar steps. 8. In growing a semiconductor crystal in a vapor phase on a substrate, the surface of the substrate is subjected to an uneven surface processing in advance, and the concave portion in the uneven surface is covered with a mask that cannot substantially grow crystals from the layer. Supplying a source gas to the substrate;
A method of manufacturing a semiconductor base material, comprising: covering an uneven surface of the substrate with a semiconductor crystal exclusively grown from an upper portion of the convex portion on the uneven surface.