JP2003160399A - Method and apparatus for growth of group iii nitride crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a high quality crystal of a group III nitride having a practical size. <P>SOLUTION: In the course of raising temperature, GaN 18 decomposes in the upper part of a crystal growth container 12 to produce a group III metal (Ga) and nitrogen. And the produced group III metal and nitrogen are supplied to Na molten liquid 17 in the lower part of the crystal growth container 12 through a mesh 14, and reacted in the Na molten liquid to make GaN crystal grown up. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor light emitting device,
The present invention relates to a crystal growth method and a crystal growth apparatus for a group III nitride crystal used as a substrate for crystal growth of electronic devices.

[0002]

2. Description of the Related Art Conventionally, a blue LED is a red or green LED.
The brightness was smaller than that of the ED, and it was difficult to put it into practical use.
In recent years, in a group III nitride compound semiconductor represented by the general formula InAlGaN, improvement of crystal growth technology by using a low temperature AlN buffer layer or a low temperature GaN buffer layer, and a low resistance p-type semiconductor layer doped with Mg have been obtained. As a result, a high-intensity blue LED has been put into practical use,
Furthermore, a semiconductor laser that oscillates in the blue wavelength region has been realized.

Generally, when a high quality semiconductor layer is epitaxially grown on a substrate, the lattice constant and the coefficient of thermal expansion of the substrate and the semiconductor layer need to be about the same. But,
Currently, there is no substrate in the world that can satisfy these requirements for group III nitride semiconductors.

Therefore, in the group III nitride, the ELO is generally formed on a different kind of substrate whose lattice constant and thermal expansion coefficient are largely different from those of the group III nitride semiconductors such as sapphire and GaAs.
A thick film GaN is grown by using a crystal growth technique such as the above, and a semiconductor laser crystal is produced by using it as a substrate.

However, a GaN substrate crystal-grown by using a heterogeneous substrate has a very large number of crystal defects with a dislocation density of about 10 ⁷ cm ^-2 , and a practical high-power laser element or electron It cannot be said that the quality is still sufficient for manufacturing a device.

On the other hand, various research institutes have made attempts to produce a GaN bulk single crystal for producing a high quality GaN substrate, but in reality, only a few millimeters have been obtained. , It is far from practical use.

Reference “Chemistry of Materials Vol.9
(1997) p.413-416 ”(Prior Art 1) describes a GaN crystal growth method using Na as a flux. In this method, sodium azide (NaN ₃ ) as a flux and metallic Ga are used as raw materials, and a reaction vessel made of stainless steel (inner dimension of vessel; inner diameter = 7.5 mm, length = 1)
(00 mm) in a nitrogen atmosphere, and the reaction vessel is filled with 60 mm.
The GaN crystal is grown by maintaining the temperature at 0 to 800 ° C. for 24 to 100 hours. This method is characterized in that crystals can be grown at a relatively low temperature of about 600 to 800 ° C., and the pressure inside the container can be as low as about 100 kg / cm ² . A GaN crystal having a size of about 1 mm can be produced by this method.

Further, in Japanese Unexamined Patent Publication No. 2001-58900 (Prior Art 2), in order to increase the size of a group III nitride crystal, a group III metal is additionally replenished during crystal growth of the group III nitride crystal. It is shown. FIG. 4 shows the method of the prior art 2. Referring to FIG. 4, in the method of the conventional technique 2, a growth vessel 102 containing a flux and a group III metal supply pipe 103 are provided in a reaction vessel 101, and a pressure is applied to the group III metal supply pipe 103 from the outside. In addition, the group III metal 104 is additionally supplied to the growth container 102. In FIG. 4, 106 is a pressurizing device, 107 is an internal space of the reaction vessel, 108 is a gas supply pipe, 109 is a pressure control device, 110 is a lower heater, and 1 is a lower heater.
11 is a side heater.

Further, Japanese Patent Laid-Open No. 2001-102316 (Prior Art 3) discloses that flux (Na) and Group III metal (G
a) A method of externally applying pressure to a melt supply pipe containing a mixed melt of (a) to additionally supply the mixed melt to a growth container containing the flux, and a flux (N
It is shown that an intermetallic compound of a) and a group III metal (Ga) is put in and partially melted to supplement the group III metal.

[0010]

However, in the prior art 1, the reaction vessel is a completely closed system, and the raw materials cannot be replenished from the outside. Therefore, the raw material is exhausted during the crystal growth and the crystal growth is stopped, and the size of the obtained crystal is as small as about 1 mm. This size is too small to put the device into practical use.

On the other hand, in the prior arts 2 and 3, since the additional supply of the raw material is performed during the crystal growth, it is possible to produce a large crystal.

However, in the prior art 2, since the vapor of flux (Na) aggregates in the low temperature part, the temperature is low.
Hole 1 of the supply pipe 103 attached to the group III metal supply pipe 103
There is a problem that 05 gets stuck. In order to prevent this, if the temperature of the metal supply pipe 103 is raised, for example, II
When the group I metal is Ga, Ga reacts with stainless steel or the like, which is the material of the metal supply pipe 103, so that the metal supply pipe 103 is also clogged.

Further, in the method of Prior Art 3, ie, the method of adding the mixed melt of the flux and the group III metal,
Since flux exists in the supply pipe, III in the supply pipe
There is a problem in that the group metal and nitrogen react with each other to form a group III nitride, which clogs the supply pipe.

When the intermetallic compound is put into the flux and partially dissolved, the crystallinity of the obtained Group III nitride is poor because the reaction with nitrogen rapidly progresses.

The present invention solves the problems of these conventional methods for producing a group III nitride bulk crystal, and makes it possible to produce a group III nitride crystal of high quality and practical size. An object of the present invention is to provide a crystal growth method and a crystal growth apparatus for a physical crystal.

[0016]

In order to achieve the above object, the invention according to claim 1 is a group III nitride crystal in which a group III metal raw material and a nitrogen raw material are reacted in a melt containing an alkali metal. In a method for growing a group III nitride crystal for growing a group III nitride, after decomposing the group III nitride into a group III metal and nitrogen,
The feature is that the group I nitride crystal is regrown.

According to a second aspect of the present invention, in the method for growing a group III nitride crystal according to the first aspect, a group III metal produced by decomposing the group III nitride is used as a group III metal source. It is characterized by growing a group nitride crystal.

According to a third aspect of the present invention, in the method for growing a group III nitride crystal according to the first aspect, the group III metal and nitrogen produced by decomposing the group III nitride are respectively added to
It is characterized by growing a group III nitride crystal as a group II metal source and a nitrogen source.

The invention according to claim 4 is the method for growing a group III nitride crystal according to any one of claims 1 to 3, wherein the reaction vessel contains the group III nitride. And a second container accommodating an alkali metal are installed, the group III nitride is decomposed in the first container, and the group III metal produced by the decomposition or The nitrogen produced by the method, or both the group III metal and nitrogen produced by the decomposition are supplied to the second container, and the crystal growth of the group III nitride crystal is performed in the second container. I am trying.

The invention according to claim 5 is the method for growing a group III nitride crystal according to claim 4, wherein the temperature of the first container is set to a high temperature and a low temperature with a decomposition temperature of the group III nitride interposed therebetween. It is characterized in that the growth of the group III nitride crystal is performed by changing it.

The invention according to claim 6 is the crystal growth method for a group III nitride crystal according to claim 4 or 5, wherein the group III nitride is attached to the inner wall of the first container. It is characterized by that.

The invention according to claim 7 is the method for growing a group III nitride crystal according to claim 6, wherein
The group nitride is characterized by being produced by reacting a group III metal raw material and a nitrogen raw material in an alkali metal melt using the first container.

The invention according to claim 8 is characterized in that the reaction vessel comprises a first vessel containing a group III nitride and a second vessel containing an alkali metal. 1
The group III nitride is decomposed in the container of, and the group III metal produced by the decomposition, or the nitrogen produced by the decomposition, or both the group III metal and the nitrogen produced by the decomposition, Of the first container and the second container, the temperature of which is independently controllable in order to perform the crystal growth of the group III nitride in the second container. It is characterized in that a control means is further provided.

The invention according to claim 9 is the crystal growth apparatus for group III nitride crystal according to claim 8, characterized in that the first container is configured to be removable.

The invention according to claim 10 is the same as that according to claim 8.
The group III nitride crystal growth apparatus described
Is characterized in that it is installed on top of the second container.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment In the first embodiment of the present invention, when a group III metal raw material is reacted with a nitrogen raw material in a melt containing an alkali metal to grow a group III nitride crystal, a group III group crystal is grown. After the nitride is decomposed into a group III metal and nitrogen, the group III nitride crystal is regrown.

More specifically, the crystal growth method according to the first embodiment of the present invention comprises a first step of decomposing a group III nitride into a group III metal and nitrogen, and a group III produced by the decomposition. The second step is to regrow Group III nitride crystals in an alkali metal melt using metal or nitrogen or both (Group III metal and nitrogen) as raw materials.

As the method of decomposing the group III nitride in the first step, for example, a method of decomposing the group III nitride by heating it at a decomposition temperature or higher, or a method of decomposing nitrogen in thermal equilibrium with the group III nitride is used. There is a method of decomposing by lowering the pressure, but other methods may be used and the method is not particularly limited. Further, the first step and the second step can be performed in the same container, or can be performed in different containers.

As the alkali metal, sodium or potassium is usually used. Also, in the present invention
The group III nitride means a compound of a group III metal selected from gallium, aluminum and indium and nitrogen (not limited to binary system, but may be ternary system or quaternary system).
Further, the group III nitride to be decomposed need not be a single crystal but may be a polycrystal. Further, the size thereof is not particularly limited, and may be fine crystals or powder.

In the first embodiment, when a group III metal raw material and a nitrogen raw material are reacted to grow a group III nitride crystal in a melt containing an alkali metal, the group III nitride is mixed with the group III metal and nitrogen. After the decomposition, the group III nitride crystal is regrown, so that the crystal growth apparatus does not require a large-scale mechanism for supplying molten metal from the outside of the reaction vessel as in the prior art. Therefore, the problem of interrupting the supply of the raw material such as clogging of the melt supply pipe, which has been a problem of the prior art, can be solved, so that a large group III nitride crystal can be grown. Moreover, the crystal growth apparatus can be simplified.

Second Embodiment In the second embodiment of the present invention, the Group III metal produced by decomposing the Group III nitride in the first embodiment is used.
A group III nitride crystal is grown as a group III metal raw material.

Here, as the nitrogen, one supplied from a nitrogen raw material can be used. The nitrogen raw material may be nitrogen gas or a compound of nitrogen and another element, which is a substance having nitrogen as a constituent element. Therefore, it may be gas, liquid, or solid, and its type is not particularly limited. Further, the nitrogen raw material can be supplied as a gas from the outside of the reaction vessel or can be melted in advance in the alkali metal melt, and the supply form thereof is not particularly limited.

As described above, in the second embodiment, the I generated by decomposing the group III nitride in the first embodiment is generated.
Since the group III metal is grown using the group II metal as the group III metal raw material, it is not necessary to supply the group III metal, and the problem of clogging of the melt supply pipe or the like can be solved. As a result, crystal growth can be continued and a large group III nitride crystal can be grown. Further, unlike the prior art 3, since it does not melt the intermetallic compound of the alkali metal and the group III metal, a rapid reaction does not occur. As a result, high quality group III nitrides can be grown.

Third Embodiment The third embodiment of the present invention is the same as the first embodiment, except that the group III metal and nitrogen produced by decomposing the group III nitride are used as the group III metal raw materials, respectively. Group III nitride crystals are grown as a nitrogen source.

Since the nitrogen produced by the decomposition escapes from the melt into the gas phase as a gas when there is a space in the reaction vessel, the reaction vessel is preliminarily filled with nitrogen gas to remove the nitrogen content. It is desirable to apply pressure.

As described above, in the third embodiment, the I generated by decomposing the group III nitride in the first embodiment is generated.
Since Group III metal and nitrogen are used as Group III metal raw materials and nitrogen raw materials, respectively, to grow Group III nitride crystals, it is not necessary to supply Group III metal raw materials and nitrogen raw materials from outside the reaction vessel. As a result, crystal growth can be performed in a closed system, and II
It is possible to solve the problem of the aggregation of alkali metal vapor to the group I metal supply pipe and the nitrogen raw material supply pipe. As a result, crystal growth can be continued and a large group III nitride crystal can be grown.

Fourth Embodiment A fourth embodiment of the present invention is based on the above-mentioned first, second and third embodiments.
In any one of the embodiments described above, a first container containing a group III nitride and a second container containing an alkali metal are installed in the reaction container, and the group III is contained in the first container. The nitride is decomposed, and the group III metal produced by the decomposition, the nitrogen produced by the decomposition, or both the group III metal produced by the decomposition and nitrogen are supplied to the second container, The group III metal is reacted with nitrogen at a predetermined temperature in the molten alkali metal in the container to grow crystals of the group III nitride.

In the fourth embodiment, the group III nitride contained in the first container is decomposed into the group III metal and nitrogen in the first container. The Group III metal produced by the decomposition is supplied to the second container and melted in the alkali metal melt. Then, the nitrogen melted in the alkali metal melt reacts with the group III metal to crystallize the group III nitride. Here, nitrogen may be prepared by previously melting the nitrogen raw material in the alkali metal melt, or may be supplied from the outside of the reaction vessel as a gas of nitrogen or a nitrogen compound and dissolved in the alkali metal melt. good. It is also possible to use nitrogen produced by the decomposition of Group III nitrides. In this case, it is desirable to fill the reaction container with nitrogen gas in advance so that a predetermined nitrogen partial pressure is applied.

The method of supplying the group III metal produced by decomposition from the first container to the second container is not particularly limited. For example, a pipe may be connected between the first container and the second container, and a Group III metal may be passed through the pipe. It is also possible to make a hole in the bottom of the first container and drop the Group III metal into the second container from there.

As described above, in the fourth embodiment, the first container containing the group III nitride and the second container containing the alkali metal are installed in the reaction container, and the first container Of the group III nitride in the container of
Group II metal, nitrogen generated by decomposition, or both group III metal and nitrogen generated by decomposition are supplied to the second container and are stored in the molten alkali metal in the second container at a predetermined temperature. Since the group III metal is reacted with nitrogen at a temperature of 3 to perform the group III nitride crystal growth, the decomposition of the starting group III nitride and the group III nitride crystal growth are performed in the first container and the second container, respectively. Can be done independently with the container,
Thereby, conditions (for example, temperature) suitable for each can be used. In this way, since crystal growth can be performed under optimum conditions, high quality crystals can be grown. In addition, since the first container and the second container are installed in the same reaction container, the group III metal generated by the thermal decomposition of the group III nitride in the first container is added to the second container by its own weight. It can also be dropped in a container.

Further, since it is not necessary to apply pressure from the outside of the reaction vessel as in the case of the conventional technique 2, the first vessel does not need to have pressure resistance. Therefore, as the first container, III
Since a material such as ceramics that does not react with the group metal (Ga) at high temperature can be used and the temperature can be raised during growth,
It is possible to solve the problem of clogging of the supply pipe due to the low-temperature agglomeration of the flux vapor, which has been a problem in prior art 2. As a result, II
The group I metal can be supplied without being depleted, the crystal growth can be continued, and a large crystal can be produced.

Fifth Embodiment In the fifth embodiment of the present invention, in the above-described fourth embodiment, the temperature of the first container is changed between high temperature and low temperature with the decomposition temperature of the group III nitride being sandwiched. The growth of group III nitride crystals is carried out.

That is, when the temperature of the first container is raised above the decomposition temperature of the group III nitride, the group III nitride is decomposed to produce the group III metal and the group III metal is supplied to the second container. Then, the crystal growth of the group III nitride crystal occurs.

On the other hand, when the temperature of the first container is made lower than the decomposition temperature of the group III nitride, the decomposition of the group III nitride is stopped and the group III metal is not supplied to the second container. Crystal growth stops.

As described above, in the fifth embodiment, the decomposition amount of the group III nitride is adjusted at the temperature of the first container to control the supply amount of the group III metal to the second container. Crystal growth can be continued under optimum conditions.

That is, in the fifth embodiment, in the fourth embodiment, the temperature of the first container is changed to a high temperature and a low temperature with the decomposition temperature of the group III nitride being sandwiched between the group III nitride crystal and the group III nitride crystal. Since the growth is performed, the decomposition of the raw material group III nitride can be controlled by the temperature of the first container, and the amount of the group III metal produced by the decomposition can be controlled. That is, since the amount of the group III metal supplied to the second container can be controlled, the concentration of the group III metal in the alkali metal melt can be controlled, and the crystal growth conditions can be optimized for growth.
Therefore, a high-quality group III nitride crystal can be produced.

Sixth Embodiment The sixth embodiment of the present invention is the same as the fourth or fifth embodiment, except that the group III nitride (the raw material group III nitride) is attached to the inner wall of the first container. It is characterized by doing.

As described above, in the sixth embodiment, the group III nitride as the raw material adheres to the inner wall of the first container in the fourth or fifth embodiment, and is thus produced by decomposition. Only the Group III metal can be supplied to the second container. Therefore, it is possible to prevent the group III nitride as a raw material from entering the second container into the second container and generating extra crystal nuclei. Therefore, polycrystallization can be prevented, and a large single crystal can be grown.

Seventh Embodiment The seventh embodiment of the present invention is the same as the sixth embodiment, except that
It is characterized in that a group III metal raw material and a nitrogen raw material are reacted in an alkali metal melt using a first container to produce a group III nitride.

Here, the group III nitride as the raw material is the first
In the molten alkali metal contained in the container, if the production conditions are appropriately selected when reacting the group III metal raw material and the nitrogen raw material, they are produced as fine crystals attached to the inner wall of the decomposition vessel. In the sixth and seventh embodiments, the raw material group III nitride is synthesized using the first container, and the group III nitride microcrystals are attached to the inner wall of the first container.

Since the alkali metal can be evaporated and removed after the raw material group III nitride is synthesized, only the group III nitride can be contained in the first container. At the stage of crystal growth, the group III nitride in the first container is used as a raw material, the group III nitride in the first container is decomposed, and the group III metal is supplied.

As described above, in the seventh embodiment, the crystal growth can be performed by placing the container in which the group III nitride, which is the raw material, is prepared in the reaction container as it is. That is,
When the group III nitride used as the raw material is produced in another container or the like, it is necessary to transfer the group III nitride to the first container, and at that time, there is a high possibility that impurities will be mixed in the raw material. However, in the seventh embodiment, since it is not necessary to transfer the group III nitride, it is possible to prevent impurities from being mixed. Therefore, a high-purity large group III nitride crystal can be produced.

Eighth Embodiment In an eighth embodiment of the present invention, a reaction vessel is provided with a first vessel containing a group III nitride and a second vessel containing an alkali metal. And in the first container III
Decompose the group nitride and supply the group III metal produced by the decomposition, or the nitrogen produced by the decomposition, or both the group III metal and the nitrogen produced by the decomposition to the second container. The second is
In order to carry out the crystal growth of the group III nitride in the container, the temperature control means for independently controlling the temperature of the first container and the second container is further provided. The temperature control method is not particularly limited,
It can be appropriately selected.

As described above, in the eighth embodiment, the first container containing the group III nitride and the second container containing the alkali metal are installed in the reaction container.
In the first container, the group III nitride is decomposed, the group III metal produced by the decomposition, or the nitrogen produced by the decomposition, or both the group III metal and the nitrogen produced by the decomposition, It is configured to supply to the second container, and the temperature of the first container and the second container can be controlled independently for crystal growth of Group III nitride in the second container. Further, since the temperature control means is further provided, the decomposition amount of the group III nitride is controlled by changing only the temperature of the first container while the crystal growth temperature is set to the optimum growth condition. Can be controlled. Therefore, the group III metal concentration in the alkali metal melt can be controlled, the crystal growth conditions can be optimized for growth, and a high quality group III nitride crystal can be produced.

Ninth Embodiment A ninth embodiment of the present invention is the same as the eighth embodiment, except that
The first container is characterized in that it is configured to be removable.

As described above, in the ninth embodiment, since the first container is configured to be removable, the group III nitriding as a raw material in the plurality of first containers is independent of crystal growth. It is possible to synthesize a product. As a result, raw material synthesis and crystal growth can be performed in parallel, time can be shortened, and cost can be reduced.

Tenth Embodiment The tenth embodiment of the present invention is characterized in that, in the eighth embodiment, the first container is installed above the second container.

As described above, in the tenth embodiment, the eighth
In the embodiment, the first container is installed on the upper part of the second container, so that the group III metal generated by the decomposition of the group III nitride in the first container is added to the second container by its own weight. It can be supplied in a container. Therefore, it is possible to efficiently supply the Group III metal into the second container without requiring a complicated mechanism for supplying the Group III metal from the first container into the second container. Therefore, the cost can be reduced.

[0060]

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

Example 1 Example 1 corresponds to the first and third embodiments of the present invention (claims 1 and 3).

FIG. 1A is a diagram (cross-sectional view) showing a structural example of the crystal growth apparatus according to the first embodiment. Note that FIG. 1 (b)
A schematic diagram of the temperature distribution is also shown in FIG.

With reference to FIG. 1A, the crystal growth apparatus of Example 1 includes a reaction vessel 10 made of stainless steel and having a closed shape.
A crystal growth container 12 that accommodates a group III metal 18 and an alkali metal melt 17 is provided therein. Reference numeral 13 is a lid of the crystal growth container 12.

Here, the crystal growth container 12 has a mesh 1
It is partitioned by 4, and the group 14 metal 18 is accommodated in the upper portion of the mesh 14. Further, in the lower part of the mesh 14, a mixed melt of an alkali metal melt and a group III metal is contained. Then, in the lower region of the mesh 14, crystal growth of group III nitride is performed.

In Example 1, the crystal growth container 1
The material of 2, lid 13 and mesh 14 is BN (boron nitride).

Further, heaters 15 and 16 are installed outside the reaction vessel 10. Here, the heater 15 and the heater 16 are configured to be able to independently control the temperature.

Next, using the crystal growth apparatus of FIG.
A crystal growth method of N will be described. First, the crystal growth container 12
Na17 as an alkali metal is stored in (the lower part of).
Next, the mesh 14 is put in to partition the crystal growth container 12 from the upper part and the lower part. Next, a GaN granular crystal 18 having a grain diameter coarser than that of the mesh 14 is placed in the upper part of the crystal growth container 12.

Next, the crystal growth container 12 is covered with the lid 13, and the crystal growth container 12 is placed in the reaction container 10. Then, the lid 11 is attached to the reaction container 10 to shut off the inside of the reaction container 10 from the external atmosphere. The operation of attaching the lid 11 to the reaction container 10 is performed in a pressurized high-purity dry nitrogen gas atmosphere.

Next, the temperatures of the heaters 15 and 16 are set as shown in FIG.
The reaction container 1 is heated to a predetermined temperature as shown in (b).
Heat 0. At this time, the temperature of the heater 15 is set to 900 ° C.
And the temperature of the heater 16 is 700 ° C. During the temperature rise,
In the upper part of the crystal growth container 12, the GaN 18 decomposes and III
Group metal (Ga) and nitrogen are produced. Then, the generated Group III metal and nitrogen are supplied to the Na melt 17 under the crystal growth container 12 through the mesh 14, and the Na melt 1
React in 7 and a GaN crystal grows.

After keeping this state for 200 hours, when the reaction vessel 10 is opened, the crystal growth vessel 12 is filled with 10 mm.
The GaN single crystals 19 and 20 of about the same size were grown.

Example 2 Example 2 is the first, second, fourth, eighth, ninth and tenth embodiments of the present invention (claim 1, claim 2, claim 4, claim 8, It corresponds to claims 9 and 10.

FIG. 2 is a diagram (cross-sectional view) showing a structural example of a crystal growth apparatus according to the second embodiment. Referring to FIG. 2, the crystal growth apparatus of Example 2 includes a second container 3 for growing crystals in a closed reaction container 30 made of stainless steel.
9 and a group III nitride (for example, GaN) 42 as a raw material
And a first container 38 for disassembling the.

Further, the inner space of the reaction container 30 is filled with nitrogen (N ₂ ) gas as a nitrogen source, and the reaction container 30
A gas supply pipe 31 that allows control of the nitrogen (N ₂ ) pressure therein is attached through the reaction vessel 30.
The gas supply pipe 31 includes a valve 32 and a pressure control device 33.
Are provided and the nitrogen pressure can be adjusted by the pressure control device 33. Further, a pressure gauge 34 for monitoring the total pressure in the reaction container 30 is installed.

In addition, a group III nitride (eg, GaN) 4
The first container 38 accommodating 2 is provided on top of the second container 39. The first container 38 is III
A hole is formed in the bottom of the region for containing the group nitride 42 so that the decomposed Group III metal (for example, Ga) melt 43 is dropped into the second container 39 below through the connected pipe. ing. In addition, the first container 38 and the second container 3
9 can be separated from each other, and the reaction container 3
Can be removed from scratch.

The material of the first container 38 and the second container 39 is BN (boron nitride).

A cover 37 is placed on the outside of the first container 38 and the second container 39 to prevent the inside of the reaction container 30 from being contaminated due to the scattering of the alkali metal or the source vapor. As the cover 37, a stainless cover can be used.

A slight gap 41 and a small gap 40 are provided between the first container 38 and the second container 39 and between the cover 37 and the reaction container 30, respectively. Through the gap 40 between the cover 37 and the reaction container 30 and the gap 41 between the first container 38 and the second container 39 into the second container 39, a melt 44 of an alkali metal and a group III metal is formed. The pressure of nitrogen gas is applied to.

On the outside of the cover 37, the heater 3
5, 36 are installed. Heater 35 and heater 3
6 can be temperature controlled independently. As a result, the heaters 35 and 36 cause the first
The temperatures of the container 38 and the second container 39 can be independently controlled to arbitrary temperatures. The heaters 35 and 36 can be removed.

Next, using the crystal growth apparatus shown in FIG.
A method of growing N will be described. First, in the first container 38, G
Add aN granular crystals or powder. Further, Na is put in the second container 39 as an alkali metal.

Then, the first container 38 is placed on the second container 39 and installed in the reaction container 30. Next, the stainless steel cover 37 is covered and the heaters 35 and 36 are installed at predetermined positions. The series of operations described above is performed in a high-purity Ar gas atmosphere.

Then, the reaction vessel 30 is closed and the valve 3
2 is closed, and the inside of the reaction container 30 is shut off from the external atmosphere.

Then, the temperature of the heaters 35 and 36 is raised to a predetermined temperature. At this time, the temperature of the first container 38 is set to 1000 ° C., and the crystal growth region in the second container 39 is set to 7 ° C.
It was set to 00 ° C.

Next, the valve 32 is opened, nitrogen gas is introduced from the nitrogen gas supply pipe 31, and the pressure is adjusted by the pressure control device 33 to make the total pressure in the reaction vessel 30 3 MPa. After maintaining this state for 200 hours, the temperature was lowered.

After reducing the pressure of the gas in the reaction vessel 30,
When the reaction container 30 is opened, the second container 39 has 10
The GaN single crystals 45 and 46 having a size of about mm were grown.

Example 3 Example 3 is the first, second, fourth, fifth, sixth, seventh, eighth, ninth and tenth embodiments of the present invention (claims 1 and 2). , Claim 4, claim 5, claim 6, claim 7, claim 8, claim 9, claim 10).

FIG. 3 is a diagram (cross-sectional view) showing a structural example of a crystal growth apparatus according to the third embodiment. The crystal growth apparatus of FIG.
Basically, it is similar to the crystal growth apparatus of FIG. That is, referring to FIG. 3, similarly to the crystal growth apparatus of FIG. 2, this crystal growth apparatus also includes a second container 69 for performing crystal growth in a closed reaction container 60 made of stainless steel. A first container 68 for decomposing the group III nitride as a raw material is provided.

Further, the inner space of the reaction vessel 60 is filled with nitrogen (N ₂ ) gas as a nitrogen source, and
A gas supply pipe 61 that allows controlling the nitrogen (N ₂ ) pressure therein is installed through the reaction vessel 60.
The gas supply pipe 61 includes a valve 62 and a pressure control device 63.
Are provided, and the nitrogen pressure can be adjusted by the pressure control device 63. Further, a pressure gauge 64 for monitoring the total pressure in the reaction container 60 is installed.

Further, in the third embodiment, the first container 68 for containing the group III nitride (eg, GaN) is provided above the second container 69, and the second container 69 is provided.
It also functions as a lid. Further, the first container 68 of the third embodiment is hollowed out in a cylindrical shape, and the group III nitride 72 is attached to the inner surface. Then, the decomposed Group III metal melt 73 travels along the inner wall of the first container 68 and is dropped into the second container 69 below. Further, the first container 68 and the second container 69 are separable from each other and can be removed from the reaction container 60.

The material of the first container 68 and the second container 69 is BN (boron nitride).

The first container 68 and the second container 69 are the reaction container 6 due to the scattering of the alkali metal or the vapor of the raw material.
A cover 67 is covered to prevent contamination of the inside. As the cover 67, a stainless cover can be used.

A gap 70 and a gap 71 are slightly formed between the first container 68 and the second container 69 and between the cover 67 and the reaction container 60, respectively. Through the gap 71 between the cover 67 and the reaction container 60 and the gap 70 between the first container 68 and the second container 69 into the second container 69, a melt 74 of an alkali metal and a Group III metal is formed. Nitrogen pressure is applied to.

On the outside of the cover 67, the heater 6
5, 66 are installed. Heater 65 and heater 6
6 can be temperature controlled independently. As a result, the heaters 65 and 66 allow the first
The temperatures of the container 68 and the second container 69 can be independently controlled to arbitrary temperatures. The heaters 65 and 66 can be removed.

Next, Ga using the crystal growth apparatus of FIG.
A method of growing N will be described. First, GaN is synthesized using the first container 68. To perform this synthesis, first turn the first container 68 upside down from that of FIG.
Alkali metal Na and metal Ga are placed in the container 68 of
And accommodate. Then, the first container 68 was placed in a reaction container similar to that shown in FIG.
Hold at 00 ° C for 100 hours. As a result, GaN microcrystals are synthesized inside the first container 68. GaN
The fine crystals of No. 3 adhere to the inner wall of the first container (decomposition container) 68, and do not fall even if the first container (decomposition container) 68 is inverted as shown in FIG.

Na used as the alkali metal
Completely evaporated and did not remain inside the first container 68.

Next, the GaN single crystal is grown in the second container 69. For this, first, the second container 69
Then, Na is added as an alkali metal. Then, as shown in FIG. 3, the first container 68 is placed on the second container 69 and placed in the reaction container 60. Then, the stainless steel cover 67 is covered and the heaters 65 and 66 are installed at predetermined positions. The above series of operations was performed in a high-purity Ar gas atmosphere.

Then, the reaction vessel 60 is closed and the valve 6
2 is closed, and the inside of the reaction container 60 is shut off from the external atmosphere.
Then, the temperature of the heaters 65 and 66 is raised to a predetermined temperature. At this time, the temperature of the first container 68 was set to 1000 ° C., and the crystal growth region in the second container 69 was set to 700 ° C.

Next, the valve 62 is opened, nitrogen gas is introduced from the nitrogen gas supply pipe 61, and the pressure is adjusted by the pressure control device 63 to make the total pressure in the reaction vessel 60 3 MPa.

Then, by controlling the temperature of the heater 65,
Growth is performed by changing the temperature of the first container 68 up and down across the decomposition temperature of the group III nitride. After maintaining this state for 200 hours, the temperature was lowered.

After reducing the pressure of the gas in the reaction vessel 60,
When the reaction container 60 is opened, the second container 69 has 10
The GaN single crystals 75 and 76 having a size of about mm were grown.

[0100]

As described above, according to the inventions of claims 1 to 7, the group III metal raw material is reacted with the nitrogen raw material in the melt containing the alkali metal to form the group III nitride. In the crystal growth method of a group III nitride crystal for growing a crystal, after decomposing the group III nitride into a group III metal and nitrogen,
Since the Group I nitride crystal is regrown, a Group III nitride crystal of high quality and practical size can be produced.

Further, according to the inventions of claims 8 to 10, the first container containing the group III nitride and the second container containing the alkali metal are provided in the reaction container. It is installed and decomposes the group III nitride in the first container and removes the group III metal produced by the decomposition, or the nitrogen produced by the decomposition, or both the group III metal and the nitrogen. It is configured to be supplied to the second container, and the temperature of each of the first container and the second container can be controlled independently in order to perform the crystal growth of the group III nitride in the second container. Since the temperature control means is further provided, a high quality and practical size group III nitride crystal can be produced.

[Brief description of drawings]

FIG. 1 is a diagram showing a crystal growth apparatus and temperature distribution of Example 1.

FIG. 2 is a diagram showing a crystal growth apparatus of Example 2.

FIG. 3 is a diagram showing a crystal growth apparatus of Example 3;

FIG. 4 is a diagram showing a crystal growth apparatus of Prior Art 2.

[Explanation of symbols]

10,30,60 Reaction vessel 11 Lid of reaction vessel 12 Crystal growth vessel 13 Crystal growth container lid 14 mesh 15,16,35,36,65,66 heater 17 Na melt 18 GaN 19,45,46 Single crystal 31,61 Gas supply pipe 32,62 valves 33,63 Pressure control device 34, 64 pressure gauge 37,67 cover 38,68 First container 39,69 Second container 40, 41, 70, 71 Gap 42,72 Group III nitride 43,73 Group III metal melt 44,74 Melt of alkali metal and group III metal

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hisanori Yamane             1-12-4 Tsurugaya, Miyagino-ku, Sendai City, Miyagi Prefecture (72) Inventor Masahiko Shimada             3-29-5 Kaigamori, Aoba-ku, Sendai City, Miyagi Prefecture F-term (reference) 4G077 AA02 BE15 CC04 CC06 EG25                       EH07

Claims (10)

[Claims] 1. A crystal growth method for a group III nitride crystal in which a group III metal raw material and a nitrogen raw material are reacted in a melt containing an alkali metal to grow a group III nitride crystal. A method for growing a group III nitride crystal, which comprises re-growing a group III nitride crystal after decomposing it into a group metal and nitrogen. 2. The crystal growth method for a Group III nitride crystal according to claim 1, wherein I generated by decomposing the Group III nitride.
A method for growing a Group III nitride crystal, which comprises growing a Group III nitride crystal using a Group II metal as a Group III metal raw material. 3. The crystal growth method for a group III nitride crystal according to claim 1, wherein I generated by decomposing the group III nitride.
A method for growing a group III nitride crystal, which comprises growing a group III nitride crystal by using a group II metal and nitrogen as a group III metal source and a nitrogen source, respectively. 4. The method for growing a group III nitride crystal according to claim 1, wherein the reaction vessel comprises a first vessel containing a group III nitride. A second container containing an alkali metal is installed, the group III nitride is decomposed in the first container, and the group III metal produced by the decomposition, or the nitrogen produced by the decomposition, or , Both the group III metal and nitrogen produced by the decomposition are supplied to the second container, and in the second container II
III characterized by performing crystal growth of group I nitride crystals III
Method for growing group-nitride crystals. 5. The method for growing a group III nitride crystal according to claim 4, wherein the temperature of the first container is changed between a high temperature and a low temperature with a decomposition temperature of the group III nitride being sandwiched between the group III nitride and the group III nitride crystal. A method for growing a Group III nitride crystal, which comprises growing a crystal. 6. The Group III nitride crystal growth method according to claim 4 or 5, wherein the Group III nitride is attached to the inner wall of the first container. Crystal growth method for physical crystals. 7. The crystal growth method for a Group III nitride crystal according to claim 6, wherein the Group III nitride is used in a first container in a alkali metal melt and a Group III metal raw material and a nitrogen raw material are used. III characterized by being made by reacting
Method for growing group-nitride crystals. 8. A reaction vessel is provided with a first vessel containing a group III nitride and a second vessel containing an alkali metal, and the group III nitride is placed in the first vessel. To decompose the substance and supply the group III metal produced by the decomposition, or the nitrogen produced by the decomposition, or both the group III metal produced by the decomposition and nitrogen to the second container. Configured and in a second container II
A group III nitride crystal characterized by further comprising temperature control means capable of independently controlling the temperature of the first container and the second container in order to perform crystal growth of the group I nitride. Crystal growth equipment. 9. The crystal growth apparatus for group III nitride crystals according to claim 8, wherein the first container is configured to be removable. 10. The crystal-growing apparatus for group III nitride crystals according to claim 8, wherein the first container is installed above the second container. Growth equipment.