JP2003171200A - Crystal growth method for compound semiconductor and compound semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for growing a crystal, by which a good quality compound semiconductor crystal thin film can be formed even when a substrate which has not been hitherto used because of its lattice mismatch or the difference in the coefficients of thermal expansion is used, and to provide a compound semiconductor device utilizing the method. <P>SOLUTION: In the crystal growth method for the compound semiconductor, a compound semiconductor 206 constituted of an element contained in an amorphous film 202 and an element contained in a raw material 204 supplied is grown on a first substrate 201 by preparing a second substrate by forming the amorphous film 202 containing at least one element constituting the compound semiconductor 206 on the first substrate 201, then preparing a third substrate by arranging areas 203 where the probability of nucleation of the compound semiconductor crystal is high on the amorphous film 202 on the surface of the second substrate, and supplying the raw material 204 containing an element which is not contained in the amorphous film 202 and constituting the compound semiconductor 206 onto the third substrate. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a compound semiconductor crystal thin film, and particularly to a compound semiconductor crystal thin film in which a good quality crystal cannot be obtained because of a large lattice mismatch and a large difference in thermal expansion coefficient between the usable substrate and the crystal. And a compound semiconductor device manufactured by using the method. INDUSTRIAL APPLICABILITY The present invention is applied to, for example, formation of a compound semiconductor crystal thin film used for a semiconductor light emitting device in a region from ultraviolet to infrared.

[0002]

2. Description of the Related Art Conventionally, compound semiconductor single crystal thin films used for semiconductor electronic devices, light emitting devices, light receiving devices, etc. have been formed by epitaxial growth on a single crystal substrate.
In order to realize a high-performance compound semiconductor device, forming a high quality single crystal thin film is an important technique, and various crystal growth techniques have been developed so far. For example, MBE (Molecular Beam Epitaxy) method and MOCVD (Metal-O
rganic Chemical Vapor Deposition) method and the like.
With the development of these growth technologies, GaAs is used as a substrate and Ga
High-speed electronic devices, light-emitting diodes, and semiconductor lasers made of As, AlAs, and mixed crystals thereof have been put to practical use, and semiconductor lasers made of InGaAsP quaternary crystal have been put to practical use with InP as a substrate.

However, although the growth technology has advanced, there are still many problems that remain. One of the representative ones is the problem of the substrate for crystal growth. In the crystal growth of a compound semiconductor, the quality of the single crystal substrate itself, the lattice mismatch between the substrate and the growing crystal, and the difference in the coefficient of thermal expansion pose problems. That is, if the substrate used has defects or the like, the growing compound semiconductor crystal also receives defects in the substrate and the growing compound semiconductor crystal has a lattice constant and a thermal expansion coefficient different from those of the substrate. If so, stress is applied during or after the crystal growth, and defects are introduced into the growth layer. Therefore, in order to obtain a good quality crystal, a good quality single crystal substrate should be used, and if a crystal that can be lattice-matched with the substrate is grown or if there is a lattice mismatch, a film thickness that does not lead to defect introduction. Techniques such as precise control and growth are taken.

Thus, in forming a compound semiconductor crystal thin film, a good quality substrate is indispensable, and the growing compound semiconductor is limited by the substrate. Furthermore, in terms of cost, GaAs and InP, which are mainly used as substrates for compound semiconductor crystal growth, are extremely expensive and problematic compared with, for example, Si substrates applied to many electronic devices. There is.

In recent years, a nitride semiconductor formed on a sapphire substrate has been used for blue-to-ultraviolet light emitting devices, and light emitting devices and the like have also been manufactured using a material having a large lattice mismatch. However, many defects due to lattice misalignment still exist in these semiconductor layers, and in order to realize higher performance devices such as improvement in light emission efficiency,
Techniques for forming higher quality crystalline thin films are needed.
Recently, a method of forming a defect-free portion in a crystal thin film by utilizing lateral growth has been studied, but this method has a drawback that the entire surface of the substrate cannot be used. Furthermore, the sapphire substrate that is currently mainly used is much more expensive than the Si substrate, and this also leaves a problem.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a crystal growth method capable of forming a good quality compound semiconductor crystal thin film using a substrate which could not be used in the past because of a lattice mismatch or a difference in thermal expansion coefficient. And to provide a compound semiconductor device manufactured using the same. In particular, it is an object of the present invention to form a high quality thin film of a nitride semiconductor such as AlN, which has not been obtained so far due to the lattice mismatch. Furthermore, it is an object to form a high quality single crystal nitride semiconductor thin film even if an inexpensive Si substrate is used. Furthermore, it is an object of the present invention to form a good quality nitride semiconductor thin film on a glass substrate which is cheaper and has a possibility of being applied to a large area light emitting device.

[0007]

The compound semiconductor crystal growth method of the present invention which achieves the above-mentioned object generally comprises an amorphous material containing one or more elements constituting the compound semiconductor on the first substrate. A step of forming a quality film to form a second substrate;
A step of forming a third substrate by arranging a region having a high nucleus generation probability of the compound semiconductor crystal on the amorphous film on the substrate surface, and forming the compound semiconductor without being included in the amorphous film. Is supplied to the third substrate, and the compound semiconductor composed of the element contained in the amorphous film and the element contained in the supplied material is grown on the first substrate. And a step of performing. Then, as a typical example, in the aluminum nitride (AlN) crystal growth method, a silicon nitride amorphous film having a thickness of 100 nm or less is formed on the first substrate to form a second substrate. A step of forming a third substrate by arranging a region having a high probability of nucleation of AlN crystals on the silicon nitride amorphous film on the surface of the second substrate, and forming an Al on the third substrate. Supply the raw material containing
And a step of growing it on the substrate.

In the above AlN crystal growth method, the following more specific embodiments are possible. The first substrate may be a silicon substrate such as a silicon single crystal substrate. In this case, the step of forming the silicon nitride amorphous film includes
It may be a step of irradiating with active nitrogen in a vacuum chamber of 1 × 10 ⁻³ [Torr] or less. In a normal chamber, the distance from the active nitrogen source to the substrate is about 100 mm or more, so the nitrogen beam from the active nitrogen source can reach the substrate without being scattered, so the pressure is 1 × 10 ^-3 [Torr ] It is necessary to set below. Further, the step of forming the silicon nitride amorphous film may be a step of heating a silicon substrate in an ammonia (NH ₃ ) atmosphere or a step of supplying an organic raw material containing nitrogen onto the heated substrate.

The first substrate may be a silicon carbide (SiC) substrate or a sapphire (Al ₂ O ₃ ) substrate. Further, the first substrate may be glass or a silicon substrate whose surface is covered with a SiO ₂ film.

In the step of arranging a region having a high nucleation probability of AlN crystals on the silicon nitride amorphous film to form a third substrate, Al is deposited by FIB on the silicon nitride amorphous film. In addition, the heat treatment may be performed at 700 ° C. or higher. There are various methods other than this example for the step of arranging the region of the AlN crystal having a high nucleus generation probability. For example, there is a method of evaporating a few atomic layers of metal such as Au, Ag, Cu, Pt, and Pd on a silicon nitride film, further heat-treating them to agglomerate, and arranging minute metal lumps on silicon nitride. . The minute metal ingots can be arranged at a certain fixed interval by controlling the heating temperature and heating time during the heat treatment. In this way, when the Al raw material is supplied and heated on a silicon nitride film in which minute metal blocks are arranged at regular intervals, for example, 2 μm,
The Al raw material that migrates on the silicon nitride film has a low migration rate in the metal lump portion and is likely to be crystallized by AlN. That is, the portion where the minute metal lumps are arranged has a high nucleation probability. According to other methods, the silicon nitride film is patterned to form the recesses, so that the portions that increase the probability of generating AlN nuclei can be arranged. By selectively patterning a substance whose interface energy when contacting with a metal is smaller than the interface energy between the substrate and the metal, a region having a high probability of nucleation is produced.

The step of supplying a raw material containing Al onto the fourth substrate to grow AlN on the first substrate is 1 × 10.
It may be a step of irradiating the fourth substrate heated to 700 ° C. or higher with an Al beam in a vacuum chamber of ⁻³ [Torr] or less. This pressure condition is determined by the condition that the molecular beam reaches the substrate without being scattered. This temperature condition is a condition for Al that has reached the substrate to sufficiently migrate on the substrate surface to form uniform AlN. The process of supplying a raw material containing Al and growing AlN on the first substrate is 700 ° C.
It may also be a step of supplying the organometallic raw material containing Al onto the fourth substrate heated as described above.

Further, a compound semiconductor device of the present invention which achieves the above object is a compound semiconductor device comprising a plurality of nitride semiconductor epitaxial growth layers stacked on a first substrate, and the compound semiconductor device is provided directly on the first substrate. It is characterized by comprising an AlN layer having a thickness of 100 nm or less grown by the above crystal growth method.

Furthermore, the compound semiconductor device of the present invention which achieves the above object is a compound semiconductor device in which a plurality of nitride semiconductors are laminated on a glass substrate, and the above-described crystal growth is performed directly on the glass substrate. The AlN film with a thickness of 50 nm or less composed of crystals with a diameter of 100 μm or less
It is characterized by being laminated in the following thickness. In this case, the light emitting device can be formed on the AlN crystal forming the AlN film directly on the glass substrate, as described in the fifth embodiment described later.

[0014]

The present invention described above forms a compound semiconductor crystal thin film according to the following action and principle. On single crystal Si substrate
A typical case of forming an AlN crystal will be described as an example. About 19% of Si and AlN have a lattice mismatch, which means that Si and AlN have high quality on Si.
It has been difficult to form AlN thin films.

First, a silicon nitride film, which is an amorphous film containing the constituent elements of the compound semiconductor AlN to be formed, is formed on a single crystal Si substrate to a thickness of 100 nm or less. Then, on the silicon nitride film, the probability of nucleation of AlN crystals is high, and
Small areas of about m or less are arranged at intervals of 10 μm or less.
For example, by FIB, Al is deposited on the silicon nitride at intervals of 2 μm in a region of about 100 nm ² and heat-treated at a temperature of about 700 ° C. or higher. It is generally known that AlN is generated when Al is supplied onto silicon nitride at a temperature of about 700 ° C. or higher (see App1ied Physics Letters 75, 484 (1999)). Therefore, by depositing Al on the silicon nitride film and heat-treating it, a minute region of AlN can be arranged on the silicon nitride film.

Next, the substrate temperature is set to 700 ° C. or higher and Al
Is supplied onto the substrate to grow AlN crystals. Al that has reached the substrate migrates on the substrate, and nuclei of AlN crystals are generated in the AlN portions arranged at 2 μm intervals on the substrate. That is, the above-mentioned portion where Al is deposited and heated to generate AlN becomes a portion having a high probability of nucleation. Furthermore, in crystal growth, the silicon nitride film formed on the Si substrate is extremely thin (100 nm or less as described above, and such a thickness is required so that the growth process described here proceeds). , When the formation of AlN begins, silicon nitride is decomposed and the portion becomes thinner. Therefore, the formed AlN crystal grows with a specific crystal orientation in accordance with the crystal orientation of the underlying single crystal Si. Furthermore, in the growth of AlN crystal, since one of the raw materials, N, is supplied from the lateral direction of the silicon nitride deposited on the Si substrate, that is, the AlN crystal, the AlN crystal is centered on the place where the first nucleus is generated. In parallel with the Si substrate surface. Such crystal growth continues until it collides with a crystal grown from a nucleus generated from an adjacent AlN portion, and eventually the entire surface of the substrate is covered with the AlN crystal.

Since the compound semiconductor is grown by the lateral growth as described above, it is less susceptible to stress due to the lattice mismatch with the underlying Si substrate, and more defect-defected than a crystal grown directly on a substrate with a large lattice mismatch. Few crystals are obtained. When a thin AlN film of 100 nm or less obtained in the above steps is used as a buffer layer and GaN is deposited thereon, a very high quality film can be obtained.

The above operation and principle are essentially the same except for the above example. For example, as the substrate, not only Si but also any single crystal semiconductor substrate can be used. Furthermore, even if an amorphous substrate made of glass or the like is used, it is possible to form a high-quality polycrystalline film composed of large grains, although not a single crystal on the entire surface. Numerically speaking, directly above the glass substrate, 100 μm was formed by the above crystal growth method.
AlN with a thickness of 50 nm or less composed of crystals with a diameter less than or equal to the diameter
Films (grains) can be stacked with a thickness of 100 nm or less to form a high quality polycrystalline film. More generally speaking, the range in which the above-mentioned action / principle is established, a step of forming a second substrate by forming an amorphous film containing one or more elements constituting a compound semiconductor on the first substrate, A region with a high probability of nucleation of compound semiconductor crystals is arranged on the amorphous film on the surface of the second substrate.
The step of forming the substrate of No. 3, and supplying the raw material containing the element which is not included in the amorphous film and constitutes the compound semiconductor onto the third substrate, and the element contained in the amorphous film and the supply thereof. And a step of growing a compound semiconductor composed of the element contained in the raw material on the first substrate.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings with reference to specific examples. (First Embodiment) A first embodiment of the present invention will be described with reference to FIG. First, a 2-inch Si (111) substrate 201 was washed with acetone and alcohol, and then treated with a 5% HF solution for 10 seconds and a 40% NH ₄ F solution for 4 minutes. Thus, the oxide film on the surface of the substrate 201 was removed, and the dangling bond of Si was terminated by hydrogen and terminated by H, and the substrate 201 was set in the MBE device (FIG. 2 (a)).

After that, heat treatment was carried out at 400 ° C. for 2 hours in the preparation room, and thereafter, it was carried into the growth room. Si substrate 1 before growth
Heat treatment was performed at 900 ° C for 20 minutes at × 10 ^-9 [Torr] or less. After that, the substrate temperature was lowered to 800 ° C., and a (7 × 7) pattern, which was a clean atomic plane, was confirmed by RHEED.

After that, active nitrogen radicals were generated using an RF (Radio Frequency) plasma cell, and the cell shutter was left closed for 5 minutes. The flow rate of nitrogen flowing through the plasma cell was 1.5 sccm, and the RF power was 300 watts. In this process, silicon nitride 202 could be deposited to 50 nm (FIG. 2 (b)).

When active nitrogen is generated in the RF plasma cell, even if the shutter of the cell is closed, a small amount of active nitrogen reaches the substrate 201 and reacts with the substrate 201 to react with the silicon nitride 202.
To generate. RHEE that silicon nitride is formed
It was confirmed by the D pattern.

After that, the substrate 201 on which the silicon nitride film 202 is deposited is set in the FIB apparatus, and Al is spread in a width of 100 nm and 2 μm.
The silicon nitride 202 was deposited at m intervals so as not to completely penetrate the silicon nitride 202.

After that, the substrate 201 was set in the MBE apparatus again, heat-treated at 400 ° C. for 3 hours in the preparation room, and then carried into the growth room.

Then, at a pressure of 1 × 10 ^-9 [Torr] or less,
It heat-processed at 00 degreeC for 30 minutes. The process of Al deposited by FIB reacts with the silicon nitride film 202 AlN ₂ 0 _3, and the further a small AlN203 (Fig 2 (c)).

After that, the shutter of the Al Knudsen cell set to the flux amount of 5 × 10 ⁻⁷ [Torr] was opened, and it was left for 10 minutes.
Irradiated with Al204. During this process, it was confirmed that the RHEED pattern changed from the silicon nitride pattern to the AlN205 pattern. When the cross section and the surface of the substrate after this step were observed by SEM, it was found that the entire substrate was covered with AlN206 (FIGS. 2 (d) to (g)). here,
FIG. 2 (f) is a sectional view of FIG. 2 (e).

Further, several substrates up to the stage before this step were prepared, the irradiation time of Al was finished at 30 seconds and 1 minute, and taken out, and the surface was observed by SEM. It was observed that a hexagonal shape showing the orientation of the AlN crystal was laterally grown around the AlN produced by FIB in advance (see FIG. 2 (e)).

Subsequently, Ga and active nitrogen by RF plasma were simultaneously supplied from the Ga Knudsen cell to this substrate,
When 5 μm GaN was grown, RHEED
The pattern showed a streak pattern. Moreover, the defect density of the produced film was measured, and it was 1 × 10 ⁻⁴ [1 / cm ² ] or less, which was a very low defect density. This is shown in Figure 1. In FIG. 1, 101 is a substrate, 102 is an AlN layer having a thickness of 100 nm or less, and 103 is a semiconductor device layer made of a nitride semiconductor.

(Second Embodiment) A second embodiment of the present invention is shown.
It will be explained using 3. First, a 2-inch Si (111) substrate 301
Was washed with acetone and alcohol, then with a 5% HF solution for 10 seconds,
Treatment with 40% NH ₄ F solution for 4 minutes to remove the oxide film on the surface, and
It was H-terminated and set in the MBE device (Fig. 3 (a)).

After that, heat treatment was carried out at 400 ° C. for 2 hours in the preparation room, and thereafter, it was carried into the growth room. Before growth, Si substrate 301
Was heat-treated at 900 ° C. for 20 minutes at 1 × 10 ⁻⁹ [Torr] or less. After that, the substrate temperature was lowered to 800 ° C., and a (7 × 7) pattern, which was a clean atomic plane, was confirmed by RHEED.

Thereafter, an RF plasma cell was used to generate active nitrogen radicals, and the shutter of the cell was kept closed.
Let stand for a minute. The flow rate of nitrogen flowing into the plasma cell is 1.5 scc
m, RF power was 300 watts. In this process, silicon nitride 302 could be deposited to a thickness of 50 nm (FIG. 3 (b)). When active nitrogen is generated in the RF plasma cell, a small amount of active nitrogen reaches the substrate 301 and reacts with the substrate 301 to generate silicon nitride 302 even if the shutter of the cell is closed. The formation of the silicon nitride 302 was confirmed by the RHEED pattern.

Then, Au303 was vapor-deposited on the substrate 301 on which the silicon nitride film 302 had been deposited at 400 ° C. in the same chamber by about 3 atomic layers (FIG. 3 (c)).

Then, at a pressure of 1 × 10 ^-9 [Torr] or less, 6
It heat-processed at 00 degreeC for 20 minutes. In this process, evaporated Au303
Agglomerates, and metal blocks 304 with a diameter of several hundreds of nanometers are spaced at 2-3 μm intervals.
(Fig. 3 (d)).

Then, the substrate temperature was quickly raised to 800 ° C., the shutter of the Al Knudsen cell set to a flux amount of 5 × 10 ⁻⁷ [Torr] was opened, and Al was irradiated for 10 minutes. During this process, it was confirmed that the RHEED pattern changed from the pattern of silicon nitride to the pattern of AlN305 and 306. When the cross section and the surface of the substrate 301 after this step were observed by SEM, it was found that the entire substrate was covered with AlN306 (FIGS. 3 (e) to (g)). Here, FIG. 3 (f) is a cross-sectional view of FIG. 3 (e).

Further, several substrates up to the stage before this step were prepared, the irradiation time of Al was finished at 30 seconds and 1 minute, and taken out, and the surface was observed by SEM.
However, it was observed that a hexagonal shape indicating the orientation of the AlN crystal was laterally grown around the metal ingot 304 on the surface of the silicon nitride (see FIG. 3 (e)).

Subsequently, Ga and active nitrogen by RF plasma were simultaneously supplied from the Ga Knudsen cell to this substrate,
When 5 μm GaN was grown, RHEED
The pattern showed a streak pattern. Further, the defect density of the produced film was measured, and it was 1 × 10 ⁻⁵ [1 / cm ² ] or less, which was a very low defect density. This is the same as the first embodiment.

(Third Embodiment) A third embodiment of the present invention is illustrated.
It will be explained using 2. First, a 2-inch Si (111) substrate 201
Was washed with acetone and alcohol, then with a 5% HF solution for 10 seconds,
40% NH_FourTreatment with F solution for 4 minutes to remove the oxide film on the surface, and
H terminated, NH _ThreeSet it on the MBE device that has a supply line
It was

After that, heat treatment was carried out at 400 ° C. for 2 hours in the preparation room, and then the film was carried into the growth room. Before growth, Si substrate 201
Was heat-treated at 800 ° C. for 30 minutes at a pressure of 1 × 10 ⁻⁸ [Torr] or less. After that, when the surface condition was observed by RHEED, a Si (1x1) pattern and a silicon nitride pattern were confirmed.

In the MBE equipment introducing NH ₃ , N
Since H ₃ remains, it is possible to obtain S by simply heat treating the Si substrate.
The i substrate surface is nitrided to form a silicon nitride film. The thickness of the silicon nitride film 202 manufactured by the same process is 5
It was 0 nm or less (FIG. 2 (b)).

After that, the substrate 201 on which the silicon nitride film 202 is deposited is set in the FIB device, and Al is spread in a width of 100 nm and 2 μm.
The silicon nitride 202 was deposited at m intervals so as not to completely penetrate the silicon nitride 202.

After that, the substrate 201 was set again in the MBE apparatus, heat-treated at 400 ° C. for 3 hours in the preparation room, and then carried into the growth room.

Then, at a pressure of 1 × 10 ⁻⁸ [Torr] or less,
It heat-processed at 00 degreeC for 30 minutes. The process of Al deposited by FIB reacts with the silicon nitride film 202 AlN ₂ 0 _3, and the further a small AlN203 (Fig 2 (c)).

After that, the shutter of the Al Knudsen cell set to the flux amount of 5 × 10 ⁻⁷ [Torr] was opened, and it was left for 10 minutes.
Irradiated with Al204. During this process, it was confirmed that the RHEED pattern changed from the pattern of silicon nitride to the pattern of AlN205 and 206. The substrate after this process
When the cross section and the surface were observed with SEM, all the substrates were AlN
It was found to be covered with 206 (Figs. 2 (d) to (g)).

Further, several substrates up to the stage before this step were prepared, and the irradiation time of Al was completed in 30 seconds and 1 minute and taken out, and the surface was observed by SEM. It was observed that a hexagonal shape showing the orientation of the AlN crystal was laterally grown around the AlN produced by FIB (see FIG. 2 (e)).

Next, NH ₃ was added to this substrate in an amount of flux.
At 1 × 10 ^-5 [Torr], Ga is flux amount 5 × 10 ^-6 [Torr],
When supplied at the same time to grow GaN of 0.5 μm, the RHEED pattern showed a streak pattern from the early stage of GaN growth. Also, the defect density of the fabricated film was measured to be 1 × 1
The defect density was very low, 0 ^-5 [1 / cm ² ] or less.

In the third embodiment, the Al and Ga raw materials were supplied from the Knudsen cell, but they can also be used by using an organometallic raw material such as trimethylaluminum or trimethylgallium.

Further, in the third embodiment, the FIB was used to form the region having a high nucleation probability. However, a method of depositing and aggregating a metal, or a patterning on a substrate in advance to generate a nucleation probability. A method of forming a high area can also be adopted.

(Fourth Embodiment) A fourth embodiment of the present invention is shown.
It will be explained using 2. First, 2 inch sapphire (0001)
After cleaning the substrate 201 with a solution of H ₃ S0 ₄ : HP0 ₄ = 3: 1, plasma C
In the VD equipment, silicon nitride film 2 using SiH ₄ and NH ₃ gas as raw materials
02 was deposited to 50 nm.

After that, the substrate 201 on which the silicon nitride film 202 is deposited is set in the FIB device, and Al is spread in a width of 100 nm and 2 μm.
The silicon nitride 202 was deposited at m intervals so as not to completely penetrate the silicon nitride 202. After that, the substrate 201 was set in the MBE apparatus, heat-treated at 400 ° C. for 3 hours in the preparation room, and then carried into the growth room.

Then, at a pressure of 1 × 10 ^-9 [Torr] or less,
It heat-processed at 00 degreeC for 30 minutes. The Al deposited by FIB processing reacts with the silicon nitride film AlN ₂ 0 _3, and the further a small AlN203 (Fig 2 (c)).

After that, the shirt of the Al Knudsen cell set to the flux amount of 5 × 10 ⁻⁷ [Torr] was opened, and it was for 10 minutes.
Irradiated with Al204. During this process, it was confirmed that the RHEED pattern changed from the pattern of silicon nitride to the pattern of AlN205 and 206. Substrate 20 after this process
When the cross section and the surface of 1 were observed with an SEM, it was found that the substrate 201 was entirely covered with AlN206 (FIG. 2 (d)-
(g)).

Furthermore, when several substrates up to the stage before this process were prepared, the irradiation time of Al was finished at 30 seconds and 1 minute, and taken out and the surface was observed by SEM. AlN203 produced by FIB in advance
A hexagonal shape indicating the crystal orientation was observed to grow laterally (see FIG. 2 (e)).

Subsequently, Ga and active nitrogen by RF plasma were simultaneously supplied from the Ga Knudsen cell to this substrate,
When 5 μm GaN was grown, RHEED
The pattern showed a streak pattern. Further, the defect density of the produced film was measured, and it was 1 × 10 ⁻⁵ [1 / cm ² ] or less, which was a very low defect density.

In the fourth embodiment, the FIB was used to form a region having a high probability of nucleation, but a method of depositing and aggregating a metal or a method of previously patterning a substrate to increase the probability of nucleation is used. A method of forming a high region can also be adopted.

(Fifth Embodiment) A fifth embodiment of the present invention is shown.
It will be explained using 2. First, 2 inch glass substrate 201
After being washed with acetone and alcohol, it was set in a plasma CVD apparatus (FIG. 2 (a)).

Then, a silicon nitride film 202 was deposited to 100 nm using SiH ₄ and NH ₃ as raw materials. The substrate temperature was 400 ° C and the RF power was 180W.

After that, the substrate 201 on which the silicon nitride film 202 is deposited is set in a FIB apparatus, and Al is 100 nm square and 2 μm wide.
The silicon nitride 202 was deposited so as not to completely penetrate the silicon nitride 202.

Then, the substrate 201 was set in the MBE apparatus, heat-treated at 400 ° C. for 30 minutes in the preparation room, and then carried into the growth room.
Then, it was heat-treated at 700 ° C. for 30 minutes under a pressure of 1 × 10 ⁻⁹ [Torr] or less. FIB Al deposited by reacts with the silicon nitride film 202 AlN ₂ 0 ₃ becomes in this process, even smaller AlN203
(Fig. 2 (c)).

After that, the shutter of the Al Knudsen cell set to the flux amount of 5 × 10 ⁻⁷ [Torr] was opened, and for 10 minutes.
Irradiated with Al204. During this process, it was confirmed that the RHEED pattern changed from the pattern of silicon nitride to the pattern of AlN205 and 206. Substrate 20 after this process
When the cross section and the surface of 1 were observed by SEM, it was found that the substrate 201 was entirely covered with AlN206 (FIG. 2 (d)-
(g)).

Further, several substrates up to the stage before this step were prepared, and the irradiation time of Al was finished at 30 seconds and 1 minute, and the surface was taken out and observed by SEM. AlN203 produced by FIB in advance
A hexagonal shape indicating the crystal orientation was observed to grow laterally (see FIG. 2 (e)).

A compound semiconductor device was manufactured using this substrate. This will be described with reference to FIG. Subsequently, Ga and K activated RF were simultaneously supplied to the substrate 401 from the Ga Knudsen cell to grow 0.5 μm GaN 403. As a result, GaN agglomerates 403 were grown in a form according to AlN agglomerates 402. Then, a large grain polycrystalline thin film could be formed.

Then, n-type GaN 404 was used with Si as a dopant.
Of 0.5 μm, In _x Ga _(1-x) N [0 <x <1] 405 of 50 nm, and p-type GaN 406 of 0.5 μm with Mg as a dopant were sequentially deposited.

After that, the substrate was taken out, and an anode electrode 407 having a diameter of 10 μm was formed at a location where Al was deposited by FIB, that is, a location corresponding to the center of the agglomerate of the nitride semiconductor 402. further,
The n-type GaN layer 404 having a width of 5 μm was etched at the center between the anode electrodes 407 to form a cathode electrode 408 having a width of 2 μm. Through the above steps, a 20 μm pitch LED two-dimensional array capable of extracting light from the glass substrate 401 side was produced (Fig. 4
(a), (b)).

In the fifth embodiment, FIB was used to form a region having a high probability of nucleation, but a glass substrate is preliminarily subjected to a fine pattern to form a silicon nitride film or a metal film. It is also possible to dispose a fine metal block by utilizing the agglomeration of the above, or to dispose a region with an increased probability of nucleation on silicon nitride.

Further, although the glass substrate is used in the fifth embodiment, the polycrystalline thin film and the light emission can be obtained in the same process even if a substrate whose surface is covered with silicon oxide by thermally oxidizing a Si substrate is used. The device can be realized. Further, as long as the substrate can withstand the heat treatment in the process of this embodiment, that is, a temperature of about 700 ° C., a substrate other than this example can be used.

[0066]

As described above, according to the present invention, it was possible to grow a compound semiconductor thin film having a large lattice mismatch with the substrate with low defects. In particular, by depositing silicon nitride on a Si substrate, arranging a region with a high probability of nucleation of AlN crystals on the silicon nitride, and further supplying an Al raw material, an AlN film with a low defect density on an inexpensive Si substrate. Could be formed. Furthermore, a good nitride semiconductor with a low defect density could be formed on this AlN layer. In addition, a compound semiconductor polycrystalline thin film having a large grain size and controlled agglomerates could be formed on an inexpensive substrate. In addition, Al on the glass substrate
An N polycrystal thin film was formed, and using it as a buffer layer, a light emitting device made of a nitride semiconductor could be formed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a compound semiconductor device according to the present invention.

FIG. 2 is a diagram showing an embodiment of a method for forming a compound semiconductor thin film according to the present invention, and FIG. 2 (a) shows a substrate made of single crystal silicon, single crystal sapphire, glass, or a silicon oxide film. FIG. 2 (b) shows the step of depositing amorphous silicon nitride on the substrate, and FIG. 2 (c) shows the silicon covering the surface.
The step of arranging a region having a high nucleus generation probability of a compound semiconductor crystal in the amorphous silicon nitride deposited in (b) is shown in FIG.
(d) is AlN by supplying Al raw material to the substrate created in the process of (c).
FIG. 2 (e) shows that nucleation occurs from the AlN portion created in the step (c), and an AlN single crystal grows in a direction parallel to the substrate. Figure 2 (f)
2E is a cross-sectional view of FIG. 2E, and FIG. 2G shows that the growth of AlN progressed and covered the entire surface of the substrate.

FIG. 3 is a view showing another embodiment of the method for forming a compound semiconductor thin film according to the present invention, and FIG. 3 (a) is a substrate of single crystal silicon, single crystal sapphire, glass, or silicon oxide. FIG. 3 (b) shows a step of depositing amorphous silicon nitride on the substrate, and FIG.
(c) shows a process of depositing a few atomic layers of metal Au on the amorphous silicon nitride deposited in (b), and Fig. 3 (d) heat-treats the substrate prepared in the process of (c) to agglomerate the metal. By doing so, the process of arranging the region with a high probability of nucleation is shown.Fig. 3 (e) shows that nucleation occurs from the metal lump portion created in the process of (c), and the AlN single crystal is parallel to the substrate. Figure 3 shows that the crystals grow.
(f) is a cross-sectional view of (e), and FIG. 3 (g) shows that the growth of AlN progressed and covered the entire surface of the substrate.

FIG. 4 (a) is a sectional configuration diagram of a compound semiconductor device according to a fifth embodiment of the present invention, and FIG. 4 (b) is a top view of the compound semiconductor device according to a fifth embodiment of the present invention. .

[Explanation of symbols] 101, 201, 301, 401 Substrate (single crystal silicon, single crystal sapphire, glass, or silicon whose surface is covered with a silicon oxide film) 102, 402 AlN layer 100 nm or less in thickness 103 Nitriding Semiconductor device layer 202, 302 Silicon nitride amorphous film 203 Fine AlN 204 Al 205, 305 AlN single crystal mass 206, 306 AlN single crystal layer or AlN polycrystal layer 303 Au deposition layer 304 Condensed Au mass 403 GaN layer 404 n-type GaN layer 405 InGaN layer 406 p-type GaN layer 407 Anode electrode 408 Cathode electrode

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4G077 AA03 BE13 DA05 EA05 ED06                       EE02 EE05 EE07 EF03 HA02                       SC01 SC08                 5F041 AA39 AA40 CA34 CA40 CA64                 5F045 AA08 AA16 AB33 AC01 AC12                       AC15 AF03 AF09 HA04 HA06                       HA24

Claims (16)

[Claims] 1. A crystal growth method for a compound semiconductor, comprising:
Forming a second substrate by forming an amorphous film containing one or more elements constituting the compound semiconductor on the substrate, and the compound semiconductor on the amorphous film on the surface of the second substrate. A step of arranging a region having a high nucleus generation probability of crystals to form a third substrate, and a raw material containing an element which is not included in the amorphous film and constitutes the compound semiconductor, on the third substrate. Supply,
A method for growing a crystal of a compound semiconductor, comprising the step of growing the compound semiconductor composed of an element contained in the amorphous film and an element contained in the supplied raw material on a first substrate. . 2. A method of crystal growth of aluminum nitride (AlN), which comprises forming a silicon nitride amorphous film having a thickness of 100 nm or less on a first substrate to form a second substrate, A step of forming a third substrate by arranging a region having a high nucleation probability of AlN crystals on the silicon nitride amorphous film on the surface of the second substrate, and a raw material containing Al on the third substrate Supply AlN first
And a step of growing the same on the substrate.
AlN crystal growth method. 3. The AlN crystal growth method according to claim 2, wherein the first substrate is a silicon substrate. 4. The AlN crystal growth method according to claim 3, wherein the step of forming the silicon nitride amorphous film is 1 × 1.
A method for growing a crystal of AlN, characterized in that it is a step of irradiating with active nitrogen in a vacuum chamber of 0 ^-3 [Torr] or less. 5. The AlN crystal growth method according to claim 3, wherein the step of forming the silicon nitride amorphous film is a step of heating a silicon substrate in an ammonia (NH ₃ ) atmosphere. And AlN crystal growth method. 6. The AlN crystal growth method according to claim 3, wherein the step of forming the silicon nitride amorphous film is a step of supplying an organic material containing nitrogen onto a heated substrate. And AlN crystal growth method. 7. The AlN crystallizing method according to claim 2, wherein the first substrate is a silicon carbide (SiC) substrate.
Alternatively, it is a sapphire (Al ₂ O ₃ ) substrate
AlN crystal growth method. 8. The AlN crystal growth method according to claim 2, wherein the first substrate is glass or a silicon substrate whose surface is covered with a SiO ₂ film. Law. 9. The AlN crystal growth method according to claim 2, wherein a region having a high nucleation probability of AlN crystals is arranged on the silicon nitride amorphous film. 3
The process of forming the substrate is performed on the silicon nitride amorphous film.
An AlN crystal growth method characterized in that it is a step of depositing Al by FIB and further performing heat treatment at 700 ° C. or higher. 10. The AlN crystal growth method according to claim 2, wherein a region having a high nucleation probability of AlN crystals is arranged on the silicon nitride amorphous film. 3. The AlN crystal growth method, wherein the step of forming the substrate of 3 is a step of vapor-depositing a metal on the silicon nitride amorphous film and further performing heat treatment. 11. The AlN crystal growth method according to claim 2, wherein a region having a high nucleation probability of AlN crystals is arranged on the silicon nitride amorphous film. The AlN crystal growth method, wherein the step of forming the substrate of 3 is a step of forming a periodic pattern in the silicon nitride amorphous film. 12. The AlN crystal growth method according to claim 2, wherein the fourth substrate is formed on the fourth substrate.
The process of supplying a raw material containing Al and growing AlN on the first substrate is performed in a vacuum chamber of 1 × 10 ⁻³ [Torr] or less at 700
A crystal growth method of AlN, characterized in that it is a step of irradiating an Al beam on a fourth substrate heated above ℃. 13. The AlN crystal growth method according to any one of claims 2 to 11, wherein the AlN crystal growth method is performed on the fourth substrate.
The step of supplying a raw material containing Al to grow AlN on the first substrate is a step of supplying an organometallic raw material containing Al to the fourth substrate heated to 700 ° C. or higher. Al
N crystal growth method. 14. A compound semiconductor device comprising a plurality of nitride semiconductor epitaxial growth layers stacked on a first substrate, wherein the compound semiconductor device is directly above the first substrate.
3. A compound semiconductor device comprising an AlN layer having a thickness of 100 nm or less grown by the crystal growth method according to any one of 3 above. 15. A compound semiconductor device comprising a plurality of nitride semiconductors laminated on a glass substrate, which has a diameter of 100 μm or less formed directly on the glass substrate by the crystal growth method according to claim 8. A compound semiconductor device characterized in that an AlN film having a thickness of 50 nm or less and composed of crystals is laminated with a thickness of 100 nm or less. 16. The compound semiconductor device according to claim 15, wherein a light emitting device is formed on the AlN crystal forming the AlN film directly on the glass substrate.