JP2003313099A - Apparatus for growing group iii nitride crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the crystal quality of a group III nitride crystal by easily setting the temperature distribution in a reaction vessel with high accuracy and performing the control of nucleation of the group III nitride and the vapor control of an alkali metal with high accuracy. <P>SOLUTION: The temperature distribution in the reaction vessel 101 can be easily set with high accuracy and the control of the nucleation of the group III nitride and the control of the vapor of the alkali metal can be conducted with high accuracy by providing a heating unit 106 in the reaction vessel 101. Accordingly, the crystal quality of the group III nitride crystal 110 can be enhanced. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention grows a group III nitride crystal that can be used as a blue-violet light source for optical disks, an ultraviolet light source (LD or LED), a blue-violet light source for electrophotography, a group III nitride electronic device, and the like. And a group III nitride crystal growth apparatus for producing the same.

[0002]

2. Description of the Related Art InGaAlN (group III nitride) devices currently used as light sources of purple to blue to green are
Most of them are M on a sapphire substrate or SiC substrate.
It is produced by crystal growth using an O-CVD method (metal organic chemical vapor deposition method), MBE method (molecular beam crystal growth method), or the like. When sapphire or SiC is used as the substrate, there are many crystal defects due to a large difference in thermal expansion coefficient or lattice constant with the group III nitride. For this,
There are problems that the device characteristics are poor, for example, it is difficult to extend the life of the light emitting device, and the operating power is increased.

Further, since the sapphire substrate is insulative, it is impossible to take out the electrode from the substrate side as in the conventional light emitting device, and the electrode from the crystal-grown group III nitride semiconductor surface side is not possible. It needs to be taken out. As a result, there is a problem that the device area becomes large, leading to high cost. Also, it was fabricated on a sapphire substrate.
In the group III nitride semiconductor device, chip separation by cleavage is difficult, and it is not easy to obtain the cavity end face required for a laser diode (LD) by cleavage. For this reason, currently, cavity end face formation by dry etching,
Alternatively, after the sapphire substrate is polished to a thickness of 100 μm or less, the resonator end face is formed in a shape close to the cleavage, but in this case also, the resonator end face and the chip separation as in the conventional LD are separated in a single process Therefore, it is impossible to easily carry out the process, and the process becomes complicated and the cost becomes high.

In order to solve these problems, it has been proposed to reduce the crystal defects by selectively laterally growing a group III nitride semiconductor film on a sapphire substrate or by taking other measures. In this method, G on the sapphire substrate
Although it becomes possible to reduce the crystal defects as compared with the case where the aN film is not selectively laterally grown, the above-mentioned problems regarding the insulating property and the cleavage due to the use of the sapphire substrate still remain. Furthermore, there are problems that the process becomes complicated and that the substrate warps due to the combination of different materials such as the sapphire substrate and the GaN thin film. These lead to higher costs.

[0005]

In order to solve the above-mentioned problems, the substrate is a GaN substrate which is the same as the group III nitride material (here, GaN) crystal-grown on the substrate. Is the most appropriate. Therefore, research on crystal growth of bulk GaN has been conducted by vapor phase growth, melt growth and the like. However, a GaN substrate having high quality and practical size has not yet been realized.

As one method for realizing a GaN substrate,
Reference `` Chemistry of Materials Vol.9 (1997) p.413-41
6 ”(hereinafter referred to as“ conventional technology ”), a GaN crystal growth method using Na as a flux has been proposed. In this method, sodium azide (NaN ₃ ) and metallic Ga are used as raw materials and sealed in a stainless steel reaction vessel (inside dimensions; inner diameter = 7.5 mm, length = 100 mm) in a nitrogen atmosphere, and the reaction vessel is sealed. 24 ~ at a temperature of 600 ~ 800 ℃
The GaN crystal is grown by holding it for 100 hours.

In the case of this prior art, 600 to 800
The crystal growth is possible at a relatively low temperature of ℃, and the pressure inside the container is relatively low at about 100 kg / cm ^2, which is a practical growth condition. However, this conventional method has a problem in that the size of the obtained crystal is small to less than 1 mm.

In order to solve the above-mentioned problems of the prior art,
The applicant of the present application has devised a large number of inventions for supplying the group III raw material and / or the group V raw material into the reaction vessel from the outside and applied for a patent.

However, in any of the group III nitride crystal growth apparatuses, a heating device for raising the temperature of the group III nitride crystal growth is provided outside the reaction vessel.

In the reaction vessel, it is necessary to control the temperature distribution in the reaction vessel in order to control the nucleation of the group III nitride and the evaporation of the alkali metal. Conventionally, however, the group III nitride undergoes crystal growth. Since the heating device for adjusting the temperature to a possible temperature was provided outside the reaction vessel, it was difficult to control the temperature distribution inside the reaction vessel with high accuracy.
It was not possible to accurately control the nucleation of group I nitrides and the evaporation of alkali metals.

Under the conventional III-nitride crystal growth conditions, the alkali metal has a vapor pressure, so that the alkali metal moves out of the mixed melt holding container. Therefore, the amount ratio of the group III metal and the alkali metal fluctuates, it becomes difficult to control the growth conditions, and there is a limit in improving the crystal quality.

According to the present invention, the temperature distribution in the reaction vessel can be set easily with high precision, and the nucleation control of the group III nitride and the vapor control of the alkali metal can be performed with high precision. An object of the present invention is to provide a group III nitride crystal growth apparatus capable of improving the crystal quality of a product crystal.

[0013]

In order to achieve the above object, the invention according to claim 1 is characterized in that in a reaction vessel, an alkali metal and a substance containing at least a Group III metal form a mixed melt, From the mixed melt and a substance containing at least nitrogen,
A group III nitride crystal growth apparatus for crystallizing a group III nitride composed of a group III metal and nitrogen, wherein heating is performed in a reaction vessel to a temperature at which the group III nitride can grow crystals. It is characterized by having means.

According to a second aspect of the present invention, in the group III nitride crystal growth apparatus according to the first aspect, one heating device is provided in the reaction vessel as a heating means, and the heating device can control the temperature. It is characterized by.

The invention according to claim 3 is the group III nitride crystal growth apparatus according to claim 1, wherein a plurality of heating devices are provided in the reaction vessel as heating means, and each heating device is independent. The feature is that the temperature can be controlled.

According to a fourth aspect of the present invention, in the group III nitride crystal growth apparatus according to the third aspect, as the plurality of heating devices, III is provided in the mixed melt or on the surface of the mixed melt.
A first heating device for controlling the temperature at which the group-nitride can grow crystals, and a second heating device provided above the first heating device and for controlling the temperature above the surface of the mixed melt. And a device.

According to a fifth aspect of the present invention, in the group III nitride crystal growth apparatus according to any one of the first to fourth aspects, a mixed melt holding container for holding the mixed melt is provided. It is characterized in that a heating element is provided.

According to the invention of claim 6, there is a second reaction vessel outside the first reaction vessel, and the alkali metal and the substance containing at least a Group III metal are mixed in the first reaction vessel. A Group III nitride crystal growth apparatus for forming a melt and growing a Group III nitride composed of a Group III metal and nitrogen from the mixed melt and a substance containing at least nitrogen. It is characterized in that a heating means is provided between the reaction container of (1) and the second reaction container.

According to a seventh aspect of the invention, in the group III nitride crystal growth apparatus according to the sixth aspect, the atmospheres of the first reaction vessel and the second reaction vessel can be controlled independently. Is characterized by.

Further, the invention according to claim 8 is the group III nitride crystal growth apparatus according to claim 6 or 7, wherein the alkali metal vapor from the mixed melt is confined in the first reaction vessel. It is characterized by being configured.

Further, the invention according to claim 9 is the group III nitride crystal growth apparatus according to any one of claims 6 to 8, wherein the inside of the first reaction vessel and the inside of the second reaction vessel It is characterized in that it can be configured to reduce the pressure difference between and.

The invention according to claim 10 is the same as claim 6
The group III nitride crystal growth apparatus according to any one of claims 9 to 9, wherein one heating device is provided as a heating unit between the first reaction container and the second reaction container, The heating device is characterized in that the temperature can be controlled.

The invention described in claim 11 is the same as claim 6.
The group III nitride crystal growth apparatus according to any one of claims 9 to 9, wherein a plurality of heating devices are provided as heating means between the first reaction container and the second reaction container, Each heating device is characterized in that the temperature can be controlled independently.

The invention according to claim 12 is the same as claim 1
In the Group III nitride crystal growth apparatus according to 1, the plurality of heating devices may be used in or on the surface of the mixed melt.
A first heating device for controlling the temperature at which the group III nitride can grow crystals, and a second heating device for controlling the temperature above the surface of the mixed melt, which is provided on the first heating device. It is characterized by having a heating device.

[0025]

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

First Embodiment FIG. 1 is a diagram showing a structural example of a first embodiment of a group III nitride crystal growth apparatus according to the present invention. Referring to FIG.
In this group III nitride crystal growth apparatus, an alkali metal (Na in the following example) and at least II are placed in a reaction vessel 101.
A mixed melt holding container 102 for holding a mixed melt 103 with a substance containing a Group I metal (Ga in the following example) is installed.

The alkali metal may be supplied from the outside or may be present in the reaction vessel 101 from the beginning.

A lid 109 is provided on the mixed melt holding container 102, and there is a small gap between the mixed melt holding container 102 and the lid 109 so that gas can flow in and out.

The reaction vessel 101 is made of stainless steel, for example. Further, the mixed melt holding container 102 and the lid 109 may be formed of, for example, BN (boron nitride), AlN, or pyrolytic BN, or tungsten (W), stainless steel (SUS), or the like. It may be formed of a metal such as nickel (Ni). Further, in the mixed melt holding container 102,
A heating element may be provided.

The group III nitride crystal growth apparatus of FIG. 1 is provided with a supply pipe 104 for supplying a substance containing at least nitrogen (for example, nitrogen gas or ammonia gas) into the reaction vessel 101. . The term "nitrogen" as used herein means a nitrogen molecule or atomic nitrogen produced from a nitrogen molecule or a compound containing nitrogen, and an atomic group or molecular group containing nitrogen, and in the present invention, nitrogen means Let's say that

Further, a substance containing at least nitrogen is contained in the container 107. Here, when nitrogen gas is used as the substance containing at least nitrogen, the container 107 stores the nitrogen gas.

When nitrogen gas is used as the substance containing at least nitrogen, the supply pipe 104 is provided with a pressure adjusting mechanism (for example, a pressure adjusting valve) 105 for adjusting the pressure of the nitrogen gas. Further, a pressure sensor 111 for detecting the pressure of nitrogen gas in the reaction vessel 101 is installed in the apparatus of FIG. 1, and the pressure sensor 111 is a pressure adjusting mechanism so that the pressure in the reaction vessel 101 becomes a predetermined pressure. It is configured to give feedback to 105.

In the embodiment of the present invention, nitrogen gas is used as the substance containing at least nitrogen, and the nitrogen gas is supplied from the container 107 installed outside the reaction container 101 to the supply pipe 104.
Can be supplied to the space 108 in the reaction vessel 101 through. At this time, the nitrogen gas is supplied from the lower side of the reaction vessel 101 as shown in FIG. The pressure of the nitrogen gas can be adjusted by the pressure adjusting mechanism 105.

Further, the present invention is characterized in that the reaction vessel 101 is provided with a heating means for raising the temperature of the group III nitride (for example, GaN) to the crystal growth possible.

Here, in the first embodiment of the present invention, the heating means detects the temperature of one heating device 106 provided in the reaction vessel 101 and the temperature of the mixed melt holding vessel 102, and the heating device And a temperature sensor 112 that feeds back to 106.

That is, in the first embodiment of the present invention,
As a heating means, one heating device 1 is provided in the reaction vessel 101.
06, the heating device 106 is temperature controllable.

In the first embodiment of the present invention, the reaction container 1
Since the heating device 106 is provided inside 01, the temperature distribution in the reaction vessel 101 can be set easily with high precision, and the nucleation control of the group III nitride and the vapor control of the alkali metal can be performed with high precision. Thus, the crystal quality of group III nitride crystal 110 can be improved.

When a heating device is provided outside the reaction vessel of the prior art, the reaction vessel is located between the heating device and the mixed melt, so that the heat between the heating device and the mixed melt is increased. The resistance increases, and the temperature control accuracy of the mixed melt cannot be increased. In the case of the present embodiment, since the thermal resistance between the heating device and the mixed melt is small, it is possible to improve the temperature control accuracy.

Second Embodiment FIG. 2 is a diagram showing a structural example of a second embodiment of the group III nitride crystal growth apparatus according to the present invention. Referring to FIG.
This group III nitride crystal growth apparatus is basically the same as that shown in FIG.
Although it has the same structure as the group II nitride crystal growth device,
The structure of the heating means in the reaction vessel 101 is shown in FIG.
It is different from the group nitride crystal growth device.

That is, in the group III nitride crystal growth apparatus of FIG. 2, the heating means detects the temperatures of the two heating devices 106 and 206 provided in the reaction vessel 101 and the mixed melt holding vessel 102. , And temperature sensors 112 and 212 that feed back the heating devices 106 and 206.

Here, the first temperature sensor 112 indicates the temperature of the lower part of the mixed melt holding container and the second temperature sensor 21 indicates
2 detects the temperature of the upper portion of the mixed melt holding container. The first temperature sensor 112 is configured to provide feedback to the first heating device 106 and the second temperature sensor 212 is configured to provide feedback to the second heating device 206. The first heating device 106 heats and controls the lower region of the mixed melt holding container, and the second heating device 206 heats and controls the upper region of the mixed melt holding container.

Of the two heating devices 106 and 206, the first heating device 106 is for controlling the temperature within the mixed melt 103 or on the surface of the mixed melt 103 to a temperature at which group III nitride crystal growth is possible. The second heating device 20 provided above the first heating device 106.
Reference numeral 6 is for controlling the temperature above the surface of the mixed melt 103.

In other words, in the second embodiment of the present invention, a plurality of (two in the example of FIG. 2) heating devices 106 and 206 are provided in the reaction vessel 101 as heating means. The heating devices 106 and 206 are characterized by independent temperature control.

In the second embodiment of the present invention, the reaction container 1
In 01, a plurality of heating devices 106, 2 are provided as heating means.
By having 06, the temperature distribution in the reaction vessel 101 can be set more accurately and easily,
The group III nitride nucleation control and the alkali metal vapor control can be performed more accurately, and the crystal quality of the group III nitride crystal 110 can be improved.

Specifically, in the second embodiment of the present invention,
The second heating device 206 raises the temperature above the surface of the mixed melt 103 to form a temperature distribution in which the temperature above the mixed melt 103 is higher. It is possible to prevent evaporation of alkali metal. That is, it is possible to suppress the movement of the alkali metal from the mixed melt holding container 102 to the outside. This allows
It is possible to prevent a change in the amount ratio of the group III metal and the alkali metal and further improve the crystal quality of the group III nitride crystal. That is, by making the amount ratio of the group III metal and the alkali metal constant, it is possible to further improve the quality of the group III nitride crystal.

Third Embodiment FIG. 3 is a diagram showing a structural example of a third embodiment of the group III nitride crystal growth apparatus according to the present invention. Referring to FIG.
In this group III nitride crystal growth apparatus, the first reactor 2
In 01, a mixed melt holding container 102 for holding a mixed melt 103 of an alkali metal (Na in the following example) and a substance containing at least a Group III metal (Ga in the following example) is installed. There is.

The alkali metal may be supplied from the outside or the first reaction vessel 201 from the beginning.
It may exist inside.

A lid 109 is provided on the mixed melt holding container 102, and there is a small gap between the mixed melt holding container 102 and the lid 109 so that gas can flow in and out.

Further, the mixed melt holding container 102 and the lid 1
09 is, for example, BN (boron nitride) or Al
It may be formed of N or pyrolytic BN, or may be formed of a metal such as tungsten (W), stainless steel (SUS), nickel (Ni), or the like. A heating element may be provided in the mixed melt holding container 102.

In addition, in the group III nitride crystal growth apparatus of the third embodiment, the second reactor is provided outside the first reaction vessel 201.
There is a reaction vessel 101 of a group III nitride (for example, Ga
A heating means is provided between the first reaction container 201 and the second reaction container 101 to bring the temperature of N) to a temperature at which crystal growth is possible.

Here, in the third embodiment of the present invention, the heating means is composed of the first reaction container 201 and the second reaction container 10.
The temperature of one heating device 106 provided between the heating device 106 and the heating device 106 is detected.
And a temperature sensor 112 that feeds back to the.

That is, in the third embodiment of the present invention,
It is characterized in that a heating means is provided between the first reaction container 201 and the second reaction container 101.

In addition, in the group III nitride crystal growth apparatus of FIG. 3, the first reaction vessel 201 and the second reaction vessel 101
Are formed of, for example, stainless steel.

In the group III nitride crystal growth apparatus of FIG. 3, the atmospheres of the first reaction vessel 201 and the second reaction vessel 101 can be controlled independently.

Further, in the group III nitride crystal growth apparatus of FIG. 3, a supply pipe 104 for supplying a substance containing at least nitrogen (for example, nitrogen gas or ammonia gas) into the first reaction vessel 201, A supply pipe 120 for supplying a substance containing at least nitrogen (for example, nitrogen gas or ammonia gas) is provided in the second reaction container 101. The term "nitrogen" as used herein means a nitrogen molecule or atomic nitrogen produced from a nitrogen molecule or a compound containing nitrogen, and an atomic group or molecular group containing nitrogen, and in the present invention, nitrogen means Let's say that

A substance containing at least nitrogen is contained in the container 107. Here, when nitrogen gas is used as the substance containing at least nitrogen, the container 107 stores the nitrogen gas.

Check valves 123 and 122 are installed in the supply pipes 104 and 120, respectively. These check valves are designed so that the gas can move from the container 107 side to the reaction container side, but the gas cannot move from the reaction container side to the outside.

When nitrogen gas is used as the substance containing at least nitrogen, the supply pipes 104 and 120 are
A pressure adjusting mechanism (for example, a pressure adjusting valve) 105 is provided to adjust the pressure of the nitrogen gas. Also, FIG.
In this apparatus, a pressure sensor 111 for detecting the pressure in the first reaction container 201 and a pressure sensor 211 for detecting the pressure in the second reaction container 101 are installed. The pressure sensor 111 and the pressure sensor 211 are configured to feed back to the pressure adjusting mechanism 105 so that the pressure in the second reaction vessel 101 becomes a predetermined pressure.

In the embodiment of the present invention, nitrogen gas is used as the substance containing at least nitrogen, and the nitrogen gas is placed outside the first and second reaction vessels 201 and 101.
It is possible to supply from 07 through the supply pipes 104 and 120 to the spaces 130 and 108 in the first and second reaction vessels 201 and 101. At this time, the pressure of the nitrogen gas can be adjusted by the pressure adjusting mechanism 105.

With such a structure, in the group III nitride crystal growth apparatus of FIG. 3, the pressure difference between the inside of the first reaction vessel 201 and the inside of the second reaction vessel 101 can be reduced.

Further, the group III nitride crystal growth apparatus of FIG. 3 is constructed so that the alkali metal vapor from the mixed melt 103 is confined in the first reaction vessel 201.

In the first and second embodiments described above, by providing the heating device in the reaction vessel 101, it is possible to obtain the effect that the temperature distribution in the reaction vessel 101 can be set easily with high accuracy. On the other hand, since the heating device is provided in the reaction vessel 101 where the alkali metal vapor exists, the heating device may be corroded.

On the other hand, in the third embodiment, the heating device 106 is installed outside the first reaction vessel 201,
As described above, since the alkali metal vapor from the mixed melt 103 can be confined in the first reaction vessel 201, it is possible to effectively prevent the heating device 106 from being corroded by being exposed to the alkali metal vapor. can do.

However, the heating device 106 is connected to the first reaction vessel 2
01 is installed outside the first reaction container 201.
If the wall thickness is large, it is difficult to accurately control the temperature distribution in the first reaction vessel 201, as described in the prior art. Therefore, the nucleation control of the group III nitride and the alkali metal There is a problem that the evaporation control cannot be performed accurately.

However, in the third embodiment,
As described above, the pressure in the first reaction vessel 201 and the second pressure
Since the pressure inside the reaction container 101 can be made substantially the same, the first reaction container 201 can be formed of a thin material (for example, thin stainless steel). Accordingly, even when the heating device 106 is installed outside the first reaction container 201, the temperature distribution in the first reaction container 201 can be accurately and easily performed because the first reaction container 201 is thin. It can be set, and the nucleation control of the group III nitride and the vapor control of the alkali metal can be accurately performed.

As described above, in the third embodiment of the present invention, since the heating device 106 is provided between the first reaction container 201 and the second reaction container 101, the heating device 106 is alkaline. It is possible to effectively prevent corrosion due to exposure to metal vapor, and it is possible to accurately and easily set the temperature distribution in the first reaction vessel 201 by the heating device 106, and to perform group III nitriding. The nucleation control of the substance and the vapor control of the alkali metal can be accurately performed, and the crystal quality of the group III nitride crystal can be improved.

Fourth Embodiment FIG. 4 is a diagram showing a structural example of a fourth embodiment of the group III nitride crystal growth apparatus according to the present invention. Referring to FIG.
This group III nitride crystal growth apparatus is basically the same as that shown in FIG.
Although it has the same structure as the group II nitride crystal growth device,
The structure of the heating means provided between the first reaction container 201 and the second reaction container 101 is different from that of the group III nitride crystal growth apparatus of FIG.

That is, in the group III nitride crystal growth apparatus of FIG. 4, the heating means is the two heating apparatuses 1 provided between the first reaction vessel 201 and the second reaction vessel 101.
06 and 206, and temperature sensors 112 and 212 that detect the temperature of the mixed melt holding container 102 and feed back to the heating devices 106 and 206.

The first temperature sensor 112 detects the temperature of the lower portion of the mixed melt holding container, and the second temperature sensor 212 detects the temperature of the upper portion of the mixed melt holding container. The first temperature sensor 112 is the first heating device 10
6 is fed back to the second temperature sensor 212.
Is configured to provide feedback to the second heating device 206. The first heating device 106 heats and controls the lower region of the mixed melt holding container, and the second heating device 20
Reference numeral 6 is adapted to control heating of the upper region of the mixed melt holding container.

Of the two heating devices 106 and 206 described above, the first heating device 106 is for controlling the temperature within the mixed melt 103 or on the surface of the mixed melt 103 to a temperature at which group III nitride crystal growth is possible. The second heating device 20 provided above the first heating device 106.
Reference numeral 6 is for controlling the temperature above the surface of the mixed melt 103.

In other words, in the fourth embodiment of the present invention, between the first reaction container 201 and the second reaction container 101, a plurality of heating means (two in the example of FIG. Heating device 106, 206, each heating device 10
The temperature of 6, 206 can be controlled independently.

Also in the group III nitride crystal growth apparatus of FIG. 4, as in the group III nitride crystal growth apparatus of FIG. 3, the pressure difference between the first reaction vessel 201 and the second reaction vessel 101 is reduced. Can be reduced.

The group III nitride crystal growth apparatus shown in FIG. 4 is also configured to confine the alkali metal vapor from the mixed melt 103 in the first reaction vessel 201.

Also in the fourth embodiment, the heating devices 106 and 206 are installed outside the first reaction vessel 201, and as described above, the alkali metal vapor from the mixed melt 103 is used for the first reaction. Since it can be confined in the container 201, it is possible to effectively prevent the heating devices 106 and 206 from being exposed to the alkali metal vapor and corroding.

Also in the fourth embodiment,
As described above, the pressure in the first reaction vessel 201 and the second pressure
Since the pressure inside the reaction container 101 can be made substantially the same, the first reaction container 201 can be formed of a thin material (for example, stainless steel). Thus, even when the heating devices 106 and 206 are installed outside the first reaction container 201, the temperature distribution in the first reaction container 201 can be accurately measured because the first reaction container 201 is thin. It can be easily set, and the nucleation control of the group III nitride and the vapor control of the alkali metal can be accurately performed.

As described above, in the fourth embodiment of the present invention, since the heating devices 106 and 206 are provided between the first reaction container 201 and the second reaction container 101,
It is possible to effectively prevent the heating devices 106 and 206 from being corroded by being exposed to the alkali metal vapor, and by the heating devices 106 and 206, the temperature distribution in the first reaction container 201 can be more accurately and easily. It is possible to control the nucleation of III-nitride and vapor control of alkali metal with higher accuracy.
The crystal quality of the group I nitride crystal can be improved.

Specifically, in the fourth embodiment of the present invention,
The second heating device 206 raises the temperature above the surface of the mixed melt 103 to form a temperature distribution in which the temperature above the mixed melt 103 is higher. It is possible to prevent evaporation of alkali metal. That is, it is possible to suppress the movement of the alkali metal from the mixed melt holding container 102 to the outside. This allows
It is possible to prevent a change in the amount ratio of the group III metal and the alkali metal and further improve the crystal quality of the group III nitride crystal. That is, by making the amount ratio of the group III metal and the alkali metal constant, it is possible to further improve the quality of the group III nitride crystal.

[0078]

As described above, according to the inventions of claims 1 to 5, the alkali metal and the substance containing at least a group III metal form a mixed melt in the reaction vessel, From the mixed melt and a substance containing at least nitrogen,
A group III nitride crystal growth apparatus for crystallizing a group III nitride composed of a group III metal and nitrogen, wherein heating is performed in a reaction vessel to a temperature at which the group III nitride can grow crystals. Since the means is provided, the temperature distribution in the reaction vessel can be easily and accurately set, and the nucleation control of the group III nitride and the vapor control of the alkali metal can be performed.

In particular, according to the inventions of claims 3 and 4, in the group III nitride crystal growth apparatus of claim 1, as a heating means, a plurality of heating devices are provided in the reaction vessel, and Since the heating device can control the temperature independently, it is possible to further suppress the movement of the alkali metal from the mixed melt holding container to the outside and to keep the amount ratio of the group III metal and the alkali metal constant. As a result, the quality of the group III nitride crystal can be improved.

That is, under the conventional group III nitride crystal growth conditions, the alkali metal has a vapor pressure,
The alkali metal was designed to move out of the mixed melt holding container. Therefore, the amount ratio of the group III metal and the alkali metal fluctuates, it becomes difficult to control the growth conditions, and there is a limit in improving the crystal quality.

On the other hand, in the inventions of claims 3 and 4, the movement of the alkali metal from the mixed melt holding container to the outside is suppressed and the amount ratio of the group III metal and the alkali metal is made constant. It is possible to improve the quality of the group III nitride crystal.

Further, according to the inventions of claims 6 to 12, there is a second reaction vessel outside the first reaction vessel, and at least II with an alkali metal is present in the first reaction vessel.
A group III nitride which forms a mixed melt with a substance containing a group I metal, and crystallizes a group III nitride composed of a group III metal and nitrogen from the mixed melt and a substance containing at least nitrogen. A crystal growth apparatus, which has a heating means between the first reaction container and the second reaction container, and therefore, as in the invention according to claim 8, mixing and melting in the first reaction container. If the alkali metal vapor from the liquid is confined, the heating device can be prevented from being corroded by the alkali metal vapor.

At this time, if the pressure difference between the first reaction container and the second reaction container is reduced as in the invention described in claim 9, the pressure in the first reaction container and the second reaction container Since the difference from the pressure in the reaction container of 1 becomes small, the wall thickness of the first reaction container can be made thin (for example, the first reaction container can be made of thin stainless steel). In this case, even if the heating device is provided outside the first reaction container, it becomes possible to favorably control the temperature distribution in the first reaction container by this heating device.

As described above, according to the sixth to twelfth aspects of the present invention, it is possible to effectively prevent the heating device from being corroded by being exposed to the alkali metal vapor, and at the same time, the first reaction. The temperature distribution in the container 201 can be easily and accurately set, the nucleation control of the group III nitride and the vapor control of the alkali metal can be performed accurately, and the crystal quality of the group III nitride crystal can be improved. Can be increased.

According to the eleventh and twelfth aspects of the invention, in particular, in the group III nitride crystal growth apparatus according to any one of the sixth to ninth aspects, the first reaction container and the A plurality of heating devices are provided as heating means between the second reaction container and each of the heating devices, and the temperature of each heating device can be controlled independently. It is possible to suppress the movement of the metal, make the amount ratio of the group III metal and the alkali metal constant, and improve the quality of the group III nitride crystal.

That is, under the conventional group III nitride crystal growth conditions, the alkali metal has a vapor pressure,
The alkali metal was designed to move out of the mixed melt holding container. Therefore, the amount ratio of the group III metal and the alkali metal fluctuates, it becomes difficult to control the growth conditions, and there is a limit in improving the crystal quality.

On the other hand, according to the eleventh and twelfth aspects of the invention, the movement of the alkali metal from the mixed melt holding container to the outside is suppressed, and the amount ratio of the group III metal and the alkali metal is kept constant. It is possible to improve the quality of the group III nitride crystal.

[Brief description of drawings]

FIG. 1 is a first III-nitride crystal growth apparatus according to the present invention.
It is a figure which shows the structural example.

FIG. 2 is a second III-nitride crystal growth apparatus according to the present invention.
It is a figure which shows the structural example.

FIG. 3 is a third group III nitride crystal growth apparatus according to the present invention.
It is a figure which shows the structural example.

FIG. 4 is a fourth group III nitride crystal growth apparatus according to the present invention.
It is a figure which shows the structural example.

[Explanation of symbols]

101 reaction vessel 102 mixed melt holding container 103 mixed melt 104 gas supply pipe 105 Nitrogen pressure control valve 106 heating device 107 nitrogen gas container 108 Space inside reaction vessel 109 Lid of mixed melt holding container 110 Group III nitride (GaN) crystal 111 Pressure sensor 112 Temperature sensor 106 first heating device 206 Second heating device 101 Second reaction vessel 201 First reaction vessel

   ─────────────────────────────────────────────────── ─── 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 AA01 AA02 BE15 CC04 EC08                       EG18 HA02 HA12

Claims (12)

[Claims] 1. A reaction vessel, in which an alkali metal and a substance containing at least a group III metal form a mixed melt, and the mixed melt and a substance containing at least nitrogen are used to form a group III metal and nitrogen. Growth of group III nitrides III
A group-nitride crystal growth apparatus, in which a reaction vessel is provided with III
A group III nitride crystal growth apparatus comprising a heating means for controlling the temperature of the group nitride to allow crystal growth. 2. The group III nitride crystal growth apparatus according to claim 1, wherein the heating means has one heating device in the reaction vessel, and the heating device is temperature controllable. Group III nitride crystal growth apparatus. 3. The group III nitride crystal growth apparatus according to claim 1, wherein a plurality of heating devices are provided in the reaction vessel as heating means, and each heating device can independently control the temperature. A group III nitride crystal growth apparatus characterized by: 4. The group III nitride crystal growth apparatus according to claim 3, wherein the plurality of heating devices are for controlling the temperature at which the group III nitride can grow crystals in the mixed melt or on the surface of the mixed melt. No. 1 heating device and a second heating device provided above the first heating device and for controlling the temperature above the surface of the mixed melt. III. Group Nitride Crystal Growth Equipment. 5. The group III nitride crystal growth apparatus according to claim 1, wherein a mixed melt holding container holding the mixed melt is provided with a heating element. A group III nitride crystal growth apparatus characterized by the above. 6. A second reaction vessel is provided outside the first reaction vessel, and in the first reaction vessel, the alkali metal and the substance containing at least a Group III metal form a mixed melt, and the mixed melt is formed. Crystal growth of a group III nitride composed of a group III metal and nitrogen from a melt and a substance containing at least nitrogen III
A group nitride crystal growth apparatus, comprising: a first reaction container and a second reaction container.
A group III nitride crystal growth apparatus comprising a heating means between the reaction vessel and the reaction vessel. 7. The group III nitride crystal growth apparatus according to claim 6, wherein the atmospheres of the first reaction container and the second reaction container can be independently controlled. Crystal growth equipment. 8. The group III nitride crystal growth apparatus according to claim 6 or 7, wherein the alkali metal vapor from the mixed melt is confined in the first reaction vessel. Group III nitride crystal growth apparatus. 9. The group III nitride crystal growth apparatus according to claim 6, wherein the pressure difference between the first reaction container and the second reaction container is reduced. A group III nitride crystal growth apparatus characterized in that 10. The group III nitride crystal growth apparatus according to claim 6, wherein a heating means is provided between the first reaction container and the second reaction container.
A group III nitride crystal growth apparatus having one heating device, the temperature of which is controllable. 11. The group III nitride crystal growth apparatus according to claim 6, wherein a heating means is provided between the first reaction container and the second reaction container.
A Group III nitride crystal growth apparatus having a plurality of heating devices, each heating device being capable of independently controlling the temperature. 12. The group III nitride crystal growth apparatus according to claim 11, wherein the plurality of heating devices are for controlling a temperature at which group III nitride crystals can grow in the mixed melt or on the surface of the mixed melt. No. 1 heating device and a second heating device provided on top of the first heating device for controlling the temperature above the surface of the mixed melt. III. Group Nitride Crystal Growth Equipment.