JP3471685B2 - Semiconductor substrate and manufacturing method thereof - Google Patents

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 method useful when a semiconductor material that is prone to dislocation defects is used.

[0002]

2. Description of the Related Art Ga is used for crystal growth of GaN-based materials.
Sapphire, because N-based materials do not have a lattice-matched substrate,
Substrates that are not lattice-matched, such as SiC, spinel, and recently Si, are used. However, in the GaN film produced due to the lack of lattice matching, 10 ¹⁰ pieces / cm ²
There are dislocations. In recent years, high-luminance light-emitting diodes, semiconductor lasers, etc. have been realized, but it is desired to reduce the dislocation density in order to improve the 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 to form a buffer layer and a GaN layer, which is used as an underlying substrate, and is partially formed on the substrate. A method has been proposed in which a high-quality crystal with a reduced dislocation density is obtained by performing crystal growth in the lateral direction by providing a selective mask and performing selective growth (for example, JP-A-10-312971).

However, according to the above method, there is a problem that the c-axis is tilted in the lateral growth direction with a small amount in the portion laterally grown on the mask layer, which causes deterioration of crystal quality. It turned out to be a problem (MRS 1998 Fall, Meeting
Proceedings G3.1). This can also be confirmed by measuring the incident azimuth dependency of the X-ray rocking curve measurement (XRC). That is, the full width at half maximum (FW) of the X-ray rocking curve due to incident X-rays from the lateral growth direction
HM) is larger than the FWHM value of X-rays from the stripe direction of the mask layer, indicating that the minute tilt (tilting) of the C axis has azimuth dependence. This suggests that many new defects may be induced in the merged portion of the lateral growth on the mask.

Although SiO ₂ is commonly used as a mask layer material, when a crystal growth layer is stacked on it, Si component migrates into this crystal growth layer, so-called auto-doping contamination. It turned out that there is a problem. Furthermore, a semiconductor material containing Al, for example, Al
When GaN is grown on the substrate with the SiO ₂ mask layer, there is also a problem that the crystal growth also occurs on the mask layer and the selective growth itself cannot be effectively performed.

As an attempt to solve such a problem, S
A substrate in which a buffer layer and a GaN layer are provided 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 to be located above the convex portion. Has proposed a method for crystal growth (MRS 1998 Fall Meeting Proceedings G3.38). According to this method, selective growth can be performed without using the SiO ₂ mask layer, and various problems caused by using the SiO ₂ mask described above can be solved.

In the above method, a sapphire substrate can be used as a base substrate, and a method therefor is also disclosed (for example, Japanese Patent Laid-Open No. 11-191659). However, the above method requires the steps of crystal growth of the buffer layer material and the GaN-based material on the sapphire base substrate, once taking out from the growth furnace, performing groove processing, and then performing crystal growth again. There is a problem that a new inconvenience occurs, the number of working steps increases, and the cost increases.

Attempts have also been made to grow a GaN-based material on a Si substrate, but when a GaN-based crystal is grown, there arises a problem that warpage or cracks are generated due to a difference in thermal expansion coefficient, and good quality crystal growth cannot be performed. there were.

Therefore, in view of the above problems, it is an object of the present invention to avoid various problems caused by using a mask layer and to simplify the manufacturing process. Another object is to solve the problem that AlGaN cannot be selectively grown, which has been difficult in the past. Furthermore, it is intended to suppress the occurrence of warpage and cracks when using a Si substrate or the like.

[0010]

The semiconductor substrate of the present invention comprises:
A semiconductor substrate comprising a substrate and a semiconductor crystal vapor-deposited on the substrate, wherein the semiconductor crystal is Al _x Ga _1-xy.
Determined by In _y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1)
It is a crystal made of a semiconductor. The substrate is the semiconductor crystal
A base substrate for growing layers, which is
Air (C surface, A surface, R surface), SiC (6H, 4H, 3
C), Si, spinel, ZnO, GaAs, or NG
O, and the crystal growth surface of the substrate is an uneven surface.
The semiconductor crystal is formed on the uneven surface of the substrate and above the convex portion.
Crystals grow from the surface of the recess and form a cavity in the recess.
Without covering the uneven surface of the substrate. Also
Is a substrate for growing the semiconductor crystal layer.
Substrate, which consists of GaN, AlGaN, and AlN
Excluding materials, and the crystal growth surface of the substrate is an uneven surface.
The semiconductor crystal is formed on the convex portion of the uneven surface of the substrate.
Crystals grow from the surface of the concave part and the surface of the concave part,
Starting from the laterally grown film and from the surface of the recess,
Film is connected to each other and covers the uneven surface of the substrate.
It is a thing.

It is preferable that the projections on the crystal growth surface of the substrate are projections having parallel stripe shapes. Furthermore <br/>, the stripe longitudinal direction of the semiconductor crystal <1-100
More preferably, the stripes are in the > direction .

A more specific semiconductor base material according to the present invention is a semiconductor base material comprising a substrate and a semiconductor crystal vapor-grown on the substrate, wherein the crystal growth surface of the substrate is an uneven surface. In the semiconductor substrate in which the semiconductor crystal is exclusively crystal-grown from above the convex portion on the uneven surface, the uneven surface is covered with the grown semiconductor crystal, and the semiconductor crystal layer and the concave portion on the uneven surface are formed. A hollow portion is formed between and.

In the semiconductor base material, the crystal growth surface of the substrate is an uneven surface, and the semiconductor crystal is
Crystal grows from the upper part of the convex part and the surface of the concave part.
The film grown laterally from the upper part and the surface of the recess
And the grown film are connected to each other to cover the uneven surface of the substrate.
The first semiconductor crystal formed by
The surface of the body crystal is an uneven surface, and [the convex portion on the uneven surface is
Crystals grow from the upper part of the and the surface of the concave part,
From the surface of the recess and the film grown in the lateral direction.
The film is connected to each other and covers the uneven surface of the substrate.
And a second semiconductor crystal formed] . Further, the surface of the second semiconductor crystal in the semiconductor base material is formed into an uneven surface, and a third semiconductor layer formed on the surface of the second semiconductor crystal by the vapor phase epitaxy method or a similar process is repeated to form multiple layers. A plurality of semiconductor layers may be provided.

In the method for producing a semiconductor substrate of the present invention, the above- mentioned semiconductor crystal is vapor-phase grown on the above-mentioned substrate.
The surface of the substrate is previously processed to have an uneven surface, and then a raw material gas is supplied to the substrate so that the upper surface of the convex portion on the uneven surface is
Crystal grows from the surface of the concave part and the surface of the concave part to raise the upper part of the convex part.
A film grown laterally as a point and a film grown from the surface of the recess.
The semiconductor film that covers the uneven surface of the substrate by connecting the
Crystal or a crystal composed of the upper part of the convex part and the surface of the concave part.
The uneven surface of the substrate can be extended without forming a cavity in the recess.
It is characterized in that it is a semiconductor crystal that covers .

[0015]

According to the present invention, by providing an uneven surface on a substrate in which no buffer layer or the like has been formed, it is possible to preliminarily prepare a ground plane which causes lateral growth capable of forming a low dislocation region from the beginning of crystal growth. It is characterized in that it is provided. That is, in the case of vapor phase growth, crystal growth may occur on the entire surface of the substrate in the initial stage of growth, but eventually the growth above the convex portion becomes dominant, and as a result, the raw material is less likely to diffuse into the concave portion, and eventually the convex portion. The uneven surface is covered with a layer grown exclusively from the upper part of the part. In the growth of this convex portion, so-called lateral growth in the direction perpendicular to the C axis occurs,
The formation of the low dislocation regions is substantially achieved without a mask layer (without using a mask layer as in the conventional case). Since the growth can be performed from the crystal growth of the layer (for example, the buffer layer) located directly on the substrate, the subsequent growth process can be continuously performed.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below 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 figure, 1 is a substrate, and 2 is a semiconductor crystal vapor-deposited on the substrate 1, respectively. 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 substrate referred to in the present invention is a substrate that serves as a base for growing various semiconductor crystal layers, and is in a state where a buffer layer for lattice matching has not yet been formed. Examples of such a substrate include sapphire (C surface, A surface, R surface), SiC (6H, 4H, 3C),
GaN, Si, spinel, ZnO, GaAs, NGO, etc. can be used, but other materials may be used as long as they meet the purpose of the invention. Moreover, you may use what turned off from these substrates.

As the semiconductor crystal grown on the substrate 1, various semiconductor materials can be used, and Al _x Ga _{1- x -y} can be used.
For In _y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1), GaN, AlGaN , InGaN, and the like having different composition ratios of x and y can be exemplified.

In particular, in the case of a semiconductor material containing Al such as AlGaN, the conventional mask method has a problem that it grows on the SiO ₂ mask layer. However, according to the present invention, such a problem is solved by the maskless method. Therefore, lateral growth of AlGaN, which was not possible conventionally, can be performed, and a high-quality film with low dislocations can be grown directly on the substrate. For this reason, light absorption by the GaN layer, which is a problem in the ultraviolet light emitting element, etc. is eliminated, and it is particularly suitable for application.

Protrusions 11 formed on the crystal growth surface of the substrate 1
Is effective when the crystal is grown exclusively from the upper part. "The crystal growth is performed exclusively from the upper part" means a state in which the crystal growth can be predominantly performed at the apex or top surface of the convex portion 11 and in the vicinity thereof, even if the growth in the concave portion occurs at the initial stage of the growth. Good, but finally indicates that the crystal growth of the convex portion 11 becomes dominant. That is, if the low dislocation region is formed by the 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 that maskless growth is possible. Hereinafter, this point will be described with reference to FIGS. 1 to 3.

1 to 3 are cross-sectional views of the projection 11 formed in a stripe shape. First, FIG. 1 illustrates a case where a substrate 1 having a deep groove depth (height of convex portion) h with respect to a groove width B is used as shown in FIG. In this case, the raw material gas does not sufficiently reach the concave portion 12 and its vicinity, and crystal growth occurs only from the upper portion of the convex portion 11. In FIG. 1 (b), 2
0 indicates the crystal unit at the start of this crystal growth. Under such a circumstance, when the crystal growth continues, the films grown in the lateral direction from the upper portion of the convex portion 11 as a starting point are connected to each other, and eventually the film shown in FIG.
As shown in (c), the concave-convex surface of the substrate 1 is covered while leaving the hollow portion 13 in the concave portion. In this case, a low dislocation region is formed in the laterally grown portion, that is, in the upper portion of the recess 12.
The quality of the produced film is improved.

FIG. 2 shows the groove depth (height of the protrusion) with respect to the groove width B.
The case where h is shallow, or the case where the substrate 1 whose groove width B is wider than the width A of the convex portion 11 is used is illustrated (see FIG. 2A). In this case, since the source gas can reach the recess 12 and its vicinity, growth in the recess 12 also occurs. Further, crystal growth also occurs from the upper portion of the convex portion 11, and as shown in FIG. 2B, the crystal units 20 and 21 are generated on the upper portion of the convex portion 11 and the surface of the concave portion 12, respectively. . Under such a circumstance, if the crystal growth continues, the films grown in the lateral direction from the upper portion of the convex portion 11 as a starting point are connected, and eventually the uneven surface of the substrate 1 is covered as shown in FIG. 2C. In this case as well, a low dislocation region is formed on the upper part of the recess 12 to improve the quality of the manufactured film.

FIG. 3 shows the groove depth (height of the protrusion) with respect to the groove width B.
The case where h is very shallow, or the case where the substrate 1 whose groove width B is much wider than the width A of the convex portion 11 is used is illustrated (see FIG. 3A). Also in this case, the source gas can reach the recess 12 and its vicinity, so that the growth in the recess 12 also occurs. Further, crystal growth also occurs from the upper portion of the convex portion 11, and as shown in FIG. 3B, the crystal units 20 and 21 are generated on the upper portion of the convex portion 11 and the surface of the concave portion 12, respectively. . Under such a circumstance, if crystal growth continues, the film grown laterally from the upper part and the film grown from the recess are connected to each other, and eventually the uneven surface of the substrate 1 is covered as shown in FIG. 3C. Become. In this case as well, it is difficult to form a low dislocation region in the portion starting from the concave portion 12, but a low dislocation region is formed in the portion laterally grown starting from the convex portion 11, which is higher than that of the entire fabricated film. Quality can be improved.

In the present invention, as long as such a convex portion 11 is not particularly limited, various shapes can be adopted. Specifically, when the groove depth (height of protrusion) h is deeper than the groove width B as described above, and when the groove depth (height of protrusion) h is shallower 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 extremely shallow with respect to B, or when the groove width B is very large relative to the width A of the convex portion 11. Especially for groove width B, groove depth (height of protrusion) h
Is deep, the raw material gas cannot substantially diffuse to the bottom during vapor phase growth, and the raw material contributes to the growth of the upper portion of the convex portion 11 efficiently, which is preferable. Further, it is preferable that the groove width B is wider than the width A of the convex portion 11 in that the region of lateral growth is increased and the low dislocation region is widened.

As a mode of forming such an uneven surface,
Examples thereof include island-shaped scattered convex portions, convex portions formed of stripe-shaped convex stripes, lattice-shaped convex portions, and convex portions in which the lines forming these are curved lines. Among these aspects of the protrusions, the aspect in which the stripe-shaped protrusions are provided is preferable because the production process can be simplified and a regular pattern can be easily produced. The longitudinal direction of the stripe may be arbitrary, but when the material to be grown on the substrate is GaN,
<11-20> direction of GaN-based material and <1-100>
Direction is preferred. Especially in the <1-100> direction,
Since it is difficult to form oblique facets such as {1-101} planes, lateral growth (lateral growth) is accelerated. As a result, it is particularly preferable in that the uneven surface can be covered more quickly.

As in the embodiment shown in FIG. 1, when the concave-convex surface of the substrate 1 is buried with the cavity 13 left, and then the light-emitting portion is grown thereon to manufacture a light-emitting element, the cavity and the semiconductor are formed. A large difference in refractive index at the interface can be obtained. As a result, the proportion of light traveling downward from the light emitting portion is reflected at this interface.
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, since it is possible to reduce the contact area between the substrate 1 and the semiconductor layer grown on the substrate 1 by leaving the cavity portion 13 left, it is possible to reduce the difference in lattice constant and difference in thermal expansion coefficient in the semiconductor. It is preferable in that the distortion caused 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, there was a problem that warpage or cracks occurred due to the difference in thermal expansion coefficient during crystal growth of a GaN-based material on a Si substrate, and high quality crystal growth could not be performed. You can solve the problem.

Further, by utilizing the fact that the contact area between the substrate 1 and the semiconductor layer 2 grown thereon can be made small, when the semiconductor layer 2 is grown 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 steps may be repeated twice in order to reduce dislocation defects. That is, as shown in FIG. 5, after crystal growth of the first semiconductor layer 2a is performed so as 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 roughened. It is also possible to form the second semiconductor crystal 2b on which the second semiconductor crystal 2b is exclusively grown by crystal growth from above the convex portion of the first semiconductor layer 2a by vapor phase growth. In this case, in particular, if the protrusion 11 of the substrate 1 and the position of the protrusion 11a formed on the first semiconductor layer 2a are vertically displaced, the second semiconductor layer 2b has the first semiconductor layer 2b. Layer 2a
Many dislocations on the upper part of the convex portion 11a do not propagate. That is, with such a configuration, the second semiconductor layer 2
The entire dislocation region b 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 further made into a concavo-convex surface, and a third semiconductor layer similarly formed by the vapor phase growth method may be formed thereon. Alternatively, the same steps may be repeated to form a plurality of semiconductor layers in multiple layers. With such a configuration, it is possible to gradually reduce the dislocation propagating each time the layers are stacked, without intentionally adjusting the positions of the upper and lower convex portions as described above.

The protrusions are formed by patterning according to the shape of the protrusions using, for example, a normal photolithography technique, and R
It can be manufactured by etching using IE technology or the like.

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

The growth conditions (gas species, growth pressure, growth temperature, etc.) for crystal growth of the semiconductor layer on the substrate may be selected according to the purpose as long as the effects of the present invention can be obtained. .

[0034]

EXAMPLES Example 1 Photoresist patterning on a c-plane sapphire substrate (width: 2 μm, period: 4 μm,
Stripe azimuth: Stripe stretching direction is <11-20> direction of sapphire substrate, and RIE (Reactive Ion)
Etching) device was used to etch a rectangular cross-section to a depth of 5 μm. The aspect ratio at this time was 2.5. After removing the photoresist, the substrate was mounted on the MOVPE device. Then, the temperature was raised to 1100 ° C. in a hydrogen atmosphere to perform thermal etching. After that, the temperature is lowered to 500 ° C., and trimethylgallium (hereinafter TM
G) was used as N raw material and ammonia was caused to flow to grow a GaN low temperature buffer layer. Subsequently, the temperature was raised to 1000 ° C. and TMG / ammonia as a raw material and silane as a dopant were flown 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 usual unevenness is not applied.

When the cross section after the growth is observed, a slight trace of the growth can be seen in the concave portion of the substrate, but as shown in FIG. 1 (c), the concave and convex portions are covered while leaving the hollow portion 13 in the concave portion to become flat. A 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 a SiO ₂ mask of the same pattern were prepared. The evaluation was InGaN (InN mixed crystal ratio = 0.2,
The pits (corresponding to dislocations) appearing after continuous growth of 100 nm thickness were counted to obtain the dislocation density. The carrier density is evaluated by Hall effect measurement, and the fluctuation of the crystal axis is X.
Evaluation was made by RC scan. The evaluation results are shown in Table 1 and FIG.

[0037]

【table 1】

It can be seen that the sample of the embodiment can reduce the dislocation density to the same level as the conventional ELO. On the other hand,
The carrier concentration was almost the same as that of GaN growth. The FWHM of XRC is 107 sec, which is the smallest, and it can be said that it is a high-quality film as a whole. From the XRC scan data of Fig. 4, the EL using the SiO ₂ mask is also used.
It was confirmed that it is a high-quality crystal without the fluctuation of the crystal axis that strengthens in the vicinity of the lateral growth direction like a GaN film formed by O growth.

[Example 2] The same as Example 1 except that the shape of the uneven portion was changed as follows. (Width: 2μ
m, period: 4 μm, stripe orientation: <11-20> of sapphire substrate, and RIE (Reactive Ion Etchi)
ng) device to a rectangular cross section to a depth of 0.5 μm. The aspect ratio at this time was 0.25.

When the cross section after the growth is observed, as shown in FIG. 2C, the concave and convex portions are buried, and the portion corresponding to the concave portion 12 is the cavity portion 13 and the GaN film 2 at the bottom thereof.
It turned out that the growth was replaced by 1. In order to evaluate this film, InGaN (InN mixed crystal ratio = 0.2,
100 nm thick) was continuously grown, and the pits appearing as above were observed. Although many pits corresponding to dislocations were found in the upper part of the convex part, few pits were observed in the laterally grown part starting from the upper part of the convex part. On the other hand, many pits were seen in the center of the recess. When the dislocation density of this film was counted, it was 9 × 10 ⁷ cm ^−3, which was higher than that in Example 1, but was lower than that in normal GaN growth. It is thought that this is because a region with many dislocations remained in the central part of the recess as a result of covering the uneven part with the part grown in the lateral direction starting from the upper part of the projection and the film grown from the recess connected to each other. To be

[Embodiment 3] An n-type AlGaN cladding layer, an InGaN light emitting layer, p
-Type AlGaN clad layer and p-type GaN contact layer were sequentially formed to produce an ultraviolet LED wafer having an emission wavelength of 370 nm. After that, electrodes are formed and elements are separated, and the LED
The element. The average value of the output of the LED chips collected on the entire wafer and the reverse current characteristic were evaluated. For comparison, an ultraviolet LED chip having the above structure manufactured by using the conventional ELO technique and an ultraviolet LED chip having the above structure manufactured using a normal sapphire substrate are used. The results of these evaluations are shown in Table 2.

[0042]

[Table 2]

As shown in Table 2, it has been found that the samples produced by using the present invention can produce high-quality LEDs with higher output and less leakage current than those of the conventional example.

[Example 4] The same as Example 1 except that trimethylaluminum (TMA) was added during the growth of the semiconductor layer. As a result, a film of AlGaN (Al composition 0.2) left a cavity in the recess, and a flat film could be grown so as to cover the uneven portion. There were few pits seen in the laterally grown portion above the concave portion as the starting point above the convex portion.
As a result, AlG that could not be achieved by conventional ELO technology
It was confirmed that high quality (low dislocation density) of the aN film was achieved by using the present invention.

Example 5 Next, an example using GaN as a substrate will be shown. Photoresist patterning on GaN substrate (width: 2 μm, period: 4 μm, stripe orientation: G
<1-100>) of aN substrate and perform 5μ with RIE device.
Etching was performed in a rectangular cross section to a depth of m. The aspect ratio at this time was 2.5. After removing the photoresist, the substrate was mounted on a MOVPE device. Then, the temperature was raised to 1000 ° C. in a mixed atmosphere of nitrogen, hydrogen and ammonia. After that, TMG / ammonia as a raw material and silane as a dopant were flown to grow an n-type GaN layer. At that time, the growth time is Ga when the normal unevenness is not applied.
The time corresponding to 4 μm in N growth was set.

When the cross section after the growth is observed, the growth on the concave portion of the substrate and the growth on the side surface of the convex portion are observed.
As shown in (c), a flat GaN film was obtained by covering the irregularities while leaving the cavity. Subsequently, the pits of the obtained film were evaluated. The pit density of GaN used as the substrate was 2 × 10 ⁵ cm ⁻³ , but when the growth of this example was carried out, it was 1 × 10 ⁵ cm ^{−3 at} the upper portion of the convex portion and 5 × 10 ³ cm ^{− at the} upper portion of the concave portion. ^It turned out that the number of pits was reduced to ³ . Thus, it was confirmed that the dislocation density can be further reduced even on a substrate having few dislocations.

[Example 6] The GaN crystal produced in Example 1 was used as a first crystal, and a second crystal was grown thereon. First, patterning a photoresist on the GaN first crystal (width: 2 μm, period: 4 μm, stripe orientation: GaN
<1-100>) of the substrate was performed, and the substrate was etched in a rectangular cross-section to a depth of 2 μm with an RIE apparatus. The patterning at this time was arranged so that the concave portion of the first crystal was located on the convex portion of the substrate. The aspect ratio at this time was 1. After removing the photoresist, the substrate was mounted on a MOVPE device. After that, 1000 ° C in a mixed atmosphere of nitrogen, hydrogen and ammonia
The temperature was raised to. After that, TMG / ammonia as a raw material and silane as a dopant were flown 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 usual unevenness is not applied.

When the cross section after growth is observed, the growth on the concave portion of the substrate is
Although long and growth is seen on the side surface of the convex part, as shown in FIG.
As shown in the figure, G
An aN film was obtained. Then, evaluate the pits of the obtained film.
8x10 when I went⁵cm ^-3The pits are decreasing
I found out that By repeating this example,
It was confirmed that there was a further dislocation density reduction effect.

[0049]

As described above, according to the semiconductor substrate and the method of manufacturing the same of the present invention, the low dislocation region can be formed without using the mask layer by providing the convex portion on the substrate. Lateral growth can be performed. Therefore, the problem caused by the formation of the mask layer is the problem of the generation of new defects in the merged portion of the lateral growth portion due to the minute tilting of the axis, the problem of autodoping, and the problem that the Al-containing semiconductor material cannot be selectively grown. Can be resolved.
Further, after providing the uneven surface 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 by one growth, which is advantageous in that the manufacturing process can be simplified. Further, it is an extremely valuable invention from the viewpoints of improving the characteristics and reducing the cost due to the effect of improving the reflectance and the phenomenon of residual strain by utilizing the cavity.

[Brief description of 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 graph showing θ-scan data of XRC.

FIG. 5 is a cross-sectional view for explaining a crystal growth state of a semiconductor substrate according to the present invention.

[Explanation of symbols]

1 substrate 11 convex 12 recess 13 Cavity 2 semiconductor layers

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Koto, Masahiro Koto, 4-3 Ikejiri, Itami City, Hyogo Prefecture, Mitsubishi Electric Wire & Cable Co., Ltd. (56) Reference JP 2000-106455 (JP, A) JP 2000 −156524 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/205

Claims (14)

(57) [Claims] 1. A semiconductor substrate comprising a substrate and a semiconductor crystal vapor-deposited on the substrate, wherein the semiconductor crystal is Al _x Ga _1-xy In _y N (0 ≦ x ≦ 1,
A crystal made of a semiconductor determined by 0 ≦ y ≦ 1)
And the substrate is a base for growing the semiconductor crystal layer.
Substrate, which is sapphire (C surface, A surface, R
Surface), SiC (6H, 4H, 3C), Si, spinel,
It is made of ZnO, GaAs, or NGO, and the crystal growth surface of the substrate is an uneven surface, and the semiconductor crystal is a portion above the convex portion on the uneven surface of the substrate.
And surface whether we crystal growth of the recess to form a cavity in the recess
A semiconductor base material that covers the uneven surface of the substrate without causing any damage . 2. The semiconductor substrate according to claim 1, wherein the projections on the crystal growth surface of the substrate are projections each having a parallel stripe shape. Wherein the longitudinal direction of the stripe is the semiconductor
The semiconductor substrate according to claim 2 , wherein the crystal has a <1-100> direction . 4. A substrate and a semiconductor device vapor-deposited on the substrate.
A semiconductor substrate comprising a body crystal, wherein the semiconductor crystal is Al _x Ga _1-xy In _y N (0 ≦ x ≦ 1,
A crystal made of a semiconductor determined by 0 ≦ y ≦ 1)
And the substrate is a base for growing the semiconductor crystal layer.
Substrate, which is a substrate, such as GaN, AlGaN, AlN
Other than the above, the crystal growth surface of the substrate is an uneven surface, and the semiconductor crystal is an upper portion of the projection on the uneven surface of the substrate.
The crystal grows from the surface of the
And a film grown laterally and a film grown from the surface of the recess
Connected to each other to cover the uneven surface of the substrate
Which is a semiconductor substrate. 5. A semiconductor crystal and a substrate in the recess.
5. The semi-mold according to claim 4, wherein there is no cavity between them.
Conductor base material. 6. The projections on the crystal growth surface of the substrate are parallel to each other.
A contract characterized by being a stripe-shaped convex portion
The semiconductor substrate according to claim 4. 7. The semiconductor is formed in the longitudinal direction of the stripe.
<1-100> direction of the crystal
Item 7. A semiconductor substrate according to item 6. 8. A substrate and a vapor-deposited semiconductor on the substrate.
A semiconductor substrate comprising a body crystal, wherein the semiconductor crystal is Al _x Ga _1-xy In _y N (0 ≦ x ≦ 1,
A crystal made of a semiconductor determined by 0 ≦ y ≦ 1)
And the substrate is a base for growing the semiconductor crystal layer.
Substrate, which is sapphire (C surface, A surface, R
Surface), SiC (6H, 4H, 3C), Si, spinel,
ZnO, composed of GaAs or NGOs,, crystal growth surface of the substrate is an irregular surface, the semiconductor crystal from the upper portion and the concave portion of the surface of the convex portion of the concavo-convex surface of the substrate
The crystal grows and the substrate is recessed without forming a cavity in the recess.
The first semiconductor crystal formed so as to cover the convex surface, and the surface of the first semiconductor crystal is an uneven surface.
Crystal grows from the upper part of the convex part and the surface of the concave part in
And the semiconductor substrate, wherein the second semiconductor crystal made form <br/> covering the concavo convex without forming a cavity in the recess, in that it consists of. 9. A substrate and a vapor-deposited semiconductor on the substrate.
A semiconductor substrate comprising a body crystal, wherein the semiconductor crystal is Al _x Ga _1-xy In _y N (0 ≦ x ≦ 1,
A crystal made of a semiconductor determined by 0 ≦ y ≦ 1)
And the substrate is a base for growing the semiconductor crystal layer.
Substrate, which is a substrate, such as GaN, AlGaN, AlN
Except that the crystal growth surface of the substrate is an uneven surface, and the semiconductor crystal is composed of the upper surface of the convex portion and the surface of the concave portion of the uneven surface of the substrate.
The crystal grows and grows laterally starting from the upper part of the protrusion.
Film and the film grown from the surface of the recess are connected to each other.
The first semiconductor crystal formed to cover the uneven surface of the substrate.
And the surface of this first semiconductor crystal as an uneven surface, and the uneven surface
Crystal grows from the upper part of the convex part and the surface of the concave part in
The film grown laterally from the upper part of the convex part and the concave part
The film grown from the surface of the part is connected to each other,
A second semiconductor crystal formed so as to cover the surface, and a semiconductor substrate. 10. A semiconductor crystal in the recess of the substrate.
10. There is no cavity between the substrate and the substrate.
The semiconductor substrate described. 11. A third semiconductor layer formed on the surface of the second semiconductor crystal in the semiconductor substrate according to claim 8 as an uneven surface and similarly formed thereon by a vapor phase growth method. And / or a semiconductor substrate having a plurality of semiconductor layers formed by repeating the same process. 12. A substrate and a half vapor-deposited on the substrate.
It is a method of manufacturing a semiconductor substrate composed of a conductor crystal.
Then, the semiconductor crystal is Al _x Ga _1-xy In _y N (0 ≦ x ≦ 1,
A crystal made of a semiconductor determined by 0 ≦ y ≦ 1)
And the substrate is a base for growing the semiconductor crystal layer.
Substrate, which is sapphire (C surface, A surface, R
Surface), SiC (6H, 4H, 3C), Si, spinel,
When vapor-depositing a semiconductor crystal on a substrate, which is made of ZnO, GaAs, or NGO , the substrate surface is preliminarily processed to have an uneven surface, and then a raw material gas is supplied to the substrate to form a convex portion on the uneven surface. Upper part and recess
It is possible to grow a crystal from the surface of the
Characterized Rukoto not cover the uneven surface of the substrate without a method of manufacturing a semiconductor substrate. 13. A substrate and a half vapor-deposited on the substrate.
It is a method of manufacturing a semiconductor substrate composed of a conductor crystal.
Then, the semiconductor crystal is Al _x Ga _1-xy In _y N (0 ≦ x ≦ 1,
A crystal made of a semiconductor determined by 0 ≦ y ≦ 1)
And the substrate is a base for growing the semiconductor crystal layer.
Substrate, which is a substrate, such as GaN, AlGaN, AlN
, Which is used for the vapor phase growth of semiconductor crystals on the substrate.
Uneven surface processing is applied to the plate surface, and then the raw material is applied to the substrate.
Gas is supplied, and the upper part of the convex part and the concave part on the uneven surface
The crystal grows from the surface of the
Films grown laterally and films grown from the surface of the recess
Are connected to each other to form a semiconductor crystal that covers the uneven surface of the substrate.
A method of manufacturing a semiconductor substrate, comprising: 14. A semiconductor crystal and a substrate in the recess.
14. There is no cavity between and,
The method for manufacturing a semiconductor substrate.