JP2007059771A - MANUFACTURING APPARATUS OF GROUP III NITRIDE CRYSTAL, GROUP III NITRIDE CRYSTAL CONTAINING Al, AND MANUFACTURING METHOD THEREOF - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing apparatus for preventing damage even if a group III nitride containing an Al element is produced. <P>SOLUTION: A first reaction tube 1 is formed of a substance having fully small reactivity to AlCl such as sapphire. First and second reaction zones are heated to 1,000°C and 1,200°C, respectively. HCl and NH<SB>3</SB>are supplied to a first reaction tube 1 and a second one 2, respectively. HCl reacts with solid Al that is a solid source 8 in the first reaction tube 1 to generate AlCl gas. The inner surface of the first reaction tube 1 is formed of sapphire to prevent reaction with AlCl. AlCl is sent to a second reaction zone. An NH<SB>3</SB>gas flow is present in the second reaction tube 2 so that the first reaction tube 1 is surrounded. Thus, AlCl immediately reacts with NH<SB>3</SB>near a region RE, thus generating gas AlN. Since AlCl is consumed entirely, it hardly reacts with quartz even if the second reaction tube 2 is made of quartz. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for producing a group III nitride crystal, and more particularly to an apparatus suitable for producing a group III nitride crystal containing an Al element.

As a method for producing a group III nitride crystal containing Al element, Ga element, etc., a gas compound containing a group III element and a gas containing a nitrogen element such as NH ₃ are subjected to a gas phase reaction, and III as a reaction product thereof There is known a method of depositing a group nitride on a predetermined single crystal substrate, a seed crystal or other predetermined base material (for example, see Patent Document 1 and Patent Document 2).

  In Patent Document 1, when a so-called HVPE method is used, specifically, when a monohalide such as AlCl or AlBr is generated as a gaseous compound for use in the reaction prior to the gas phase reaction, the reaction of the reaction is performed. In order to solve the problem of reaction with quartz, which is generally used as a material for the container, and damaging the reaction container, the heating temperature during the reaction is set to 700 ° C. or lower to replace the monohalide. An embodiment is disclosed in which a halide is produced and used to produce a group III nitride.

Patent Document 2 discloses that when a so-called MOCVD method is used, specifically, when a trimethylated group III element is reacted with NH ₃ as the above gas phase reaction, at the outlet of the trimethylated supply pipe. In order to avoid generation and adhesion of reaction products, an embodiment is disclosed in which the supply pipe is composed of sapphire, calcium fluoride, magnesium fluoride, or barium fluoride.

JP 2003-303774 A Japanese Patent No. 3142054

  According to the method disclosed in Patent Document 1, even if quartz is used as a reaction vessel, the breakage is surely prevented. However, since the heating temperature in the reaction is limited to 700 ° C. or less, the group III There is a problem that it is difficult to increase the reaction rate in the formation of nitride.

  The present invention has been made in view of the above problems, and an apparatus capable of producing a group III nitride containing an Al element without causing damage to the reaction vessel in the production process. The purpose is to provide.

  In order to solve the above-mentioned problem, the invention of claim 1 is an apparatus for producing a group III nitride crystal, in which a group III element solid is reacted with a hydrogen halide provided from a predetermined source to form a group III A first reaction tube for generating an element halide, and a spatially communicating with the first reaction tube, in the vapor phase containing the halide and a nitrogen element-containing gas supplied from a predetermined supply source inside A second reaction tube for reacting to form a group III nitride and further precipitating the group III nitride on a predetermined seed crystal, wherein at least an inner surface of the first reaction tube has the group III element It is characterized by being formed of a material that is hardly reactive to monohalides.

  The invention according to claim 2 is the manufacturing apparatus according to claim 1, wherein the second reaction tube is inserted into the second reaction tube with one end of the first reaction tube being opened. In the pipe, the nitrogen element-containing gas is supplied so that the flow of the nitrogen element-containing gas surrounds the one end.

  The invention of claim 3 is a method for producing a group III nitride crystal containing an Al element, which reacts with a solid source of at least a group III element containing solid Al and a hydrogen halide provided from a predetermined source. A first reaction step of generating a group III element halide, and a second reaction step of generating a group III nitride by performing a gas phase reaction between the halide and a nitrogen element-containing gas provided from a predetermined source. And a precipitation step of precipitating the group III nitride on a predetermined seed crystal, wherein the first reaction step comprises a first reaction in which at least an inner surface is formed of a hardly reactive substance with respect to Al monohalide. It is performed inside the tube.

  The invention of claim 4 is the manufacturing method according to claim 3, wherein one end of the first reaction tube is inserted into the second reaction tube in an open state, and the second reaction tube The reaction step is performed while supplying the nitrogen element-containing gas so that the flow of the nitrogen element-containing gas surrounds the one end in the second reaction tube.

  Further, the invention of claim 5 is the manufacturing method according to claim 3 or claim 4, wherein the group III nitride has a content ratio of Al element equal to or higher than the content ratio of Al element in the manufactured group III nitride. An epitaxial substrate obtained by epitaxially growing an object on a predetermined base material is used as the predetermined seed crystal.

  The invention according to claim 6 is the manufacturing method according to claim 5, wherein an epitaxial substrate on which AlN is epitaxially grown is used as the predetermined seed crystal.

  The invention according to claim 7 is the manufacturing method according to any one of claims 3 to 6, wherein the first reaction step is performed in a temperature range in which a monohalide is generated as the halide. It is characterized by that.

  The invention of claim 8 is a manufacturing apparatus according to claim 1 or claim 2, wherein a group III element solid containing at least Al as the group III element solid is used as the group III element solid. It is produced by using.

  According to a ninth aspect of the invention, a group III nitride crystal containing an Al element is produced by the production method according to any one of the third to seventh aspects.

  According to the first to ninth aspects of the present invention, even when the halide to be produced is Al halide, the first reaction tube is not damaged, and the production of the group III nitride crystal is not affected. Al halide can be provided.

In particular, according to the inventions of claim 2 and claim 4, since most of the halogenated Al is consumed by the reaction with the NH ₃ gas, the second reaction tube is formed of a substance that easily reacts with the halogenated Al. Even so, it will not be damaged by the reaction.

  Further, according to the inventions of claim 5 and claim 6, since the group III nitride crystal deposited on the seed crystal is not cracked, a group III nitride crystal of good crystal quality is obtained. I can do it.

  Further, according to the invention of claim 7, a group III nitride crystal can be produced more efficiently than the case of producing a monohalide through the production of a trihalide.

<Device configuration>
FIG. 1 is a schematic cross-sectional view schematically showing the structure of a group III nitride crystal production apparatus 10 according to an embodiment of the present invention. The production apparatus 10 mainly generates a group III nitride by a gas phase reaction between a halide of a group III element and a substance containing nitrogen, and deposits it on a substrate to obtain a desired group III nitride crystal. It can be done.

The production apparatus 10 mainly includes a first reaction tube 1, a second reaction tube 2, a first heating unit 3, a second heating unit 4, an HCl gas supply source 5, an NH ₃ gas supply source 6, And an exhaust means 7.

  The first reaction tube 1 is a cylindrical member that is inserted into the second reaction tube 2 with one end thereof being open. The first reaction tube 1 and the second reaction tube 2 need to be spatially connected, but need not necessarily be configured in the manner shown in FIG. Further, an HCl gas supply source 5 is connected to the other end. The first reaction tube 1 is formed entirely or at least on the inner surface 1s thereof by a substance having a sufficiently small reactivity with AlCl (this is called an AlCl hardly reactive substance). For example, BN, AlN, sapphire, alumina and the like can be used as the AlCl hardly reactive substance, but sapphire and alumina are preferable from the viewpoint of ease of processing. In the case of a complicated shape, it is desirable to form the main body from a quartz member and coat at least the inner surface with an AlCl hardly reactive material. A solid source 8 can be placed inside the first reaction tube 1. For example, the solid source 8 is, for example, a single solid Al or a mixture of solid Al and solid Ga or solid In. FIG. 1 shows a state where the solid source 8 is placed. In FIG. 1, for the sake of convenience, one solid source is used, but two or more solid sources can be individually mounted, and a reaction tube of raw materials other than Al can be provided as a separate system.

  The second reaction tube 2 is also a tubular member, and the first reaction tube 1 is inserted into a part thereof as described above. That is, it can be said that the production apparatus 10 is configured by a reaction tube partially having a double structure.

  However, the 2nd reaction tube 2 also has a part in which the 1st reaction tube 1 of considerable length does not exist. Hereinafter, the portion where the first reaction tube exists in the second reaction tube 2 including the inside of the first reaction tube 1 is referred to as a first reaction zone, and the portion where the first reaction tube does not exist is referred to as a second reaction zone. In the second reaction zone, a seed crystal 9 for precipitating group III nitride can be placed. FIG. 1 shows a state where the seed crystal 9 is placed. In FIG. 1, the seed crystal 9 is displayed so as to be placed horizontally with respect to the gas flow, but the seed crystal 9 may be placed vertically with respect to the gas flow.

  As the seed crystal 9, for example, a predetermined single crystal substrate such as sapphire can be used, or a so-called epitaxial substrate in which AlN is epitaxially grown on a predetermined base material may be used. When forming a group III nitride crystal containing Al on an epitaxial substrate formed by epitaxially growing a group III nitride containing Al, the abundance ratio of Al in the former group III nitride is the latter group III nitride. It is desirable from the viewpoint of producing a good group III nitride crystal in the production apparatus 10 that the Al content in the nitride is not more than the abundance ratio. If this is not satisfied, cracks may occur in the manufactured group III nitride crystal. In addition, as for the group III nitride crystal containing Al to precipitate, it is desirable that the abundance ratio of Al is a majority of all Group III raw materials, that is, 50% or more, and among them, AlN is most desirable. This is because the advantage of the present invention that the supply of the Al raw material can be performed efficiently can be most utilized.

  As the material of the second reaction tube 2, a material that is stable in a heating temperature range described later and does not react with the generated group III nitride is used. For example, the above-described AlCl hardly reactive material may be used. However, from the viewpoint of cost and ease of processing, it is practical and preferable to use quartz. This is because when a quartz member is used, it is possible to realize a complicated shape for ensuring the uniformity of the film thickness from the ease of processing, and it is easy to cope with an increase in size in terms of cost. . The problem of reaction with the group III nitride when quartz is used will be described later.

An NH ₃ gas supply source 6 is connected to the end of the second reaction tube 2 where the first reaction tube 1 is inserted. An exhaust means 7 is connected to the other end.

  The first heating means 3 and the second heating means 4 are each provided so as to surround the second reaction tube 2. The first heating means 3 is provided for heating the first reaction zone, and the second heating means 4 is provided for heating the second reaction zone. Both the first heating means 3 and the second heating means 4 are heaters that generate heat when energized by an energizing means (not shown). That is, it can be said that the manufacturing apparatus 10 has a configuration as an electric furnace that can perform heating at different heating temperatures in the first reaction zone and the second reaction zone. However, the heating temperature of the first reaction zone and the second reaction zone may be the same, and an integrated electric furnace may be used.

The HCl gas supply source 5 is provided to supply the HCl gas together with the carrier gas to the inside of the first reaction tube 1. Note that the HCl gas is exemplified as one embodiment of the hydrogen halide gas. The NH ₃ gas supply source 6 is provided to supply the NH ₃ gas together with the carrier gas to the inside of the second reaction tube 2. For example, N ₂ can be used as the carrier gas. Specific configurations of these supply sources can be realized using known techniques.

  The exhaust unit 7 performs a process of exhausting the inside of the second reaction tube 2. The exhaust means 7 is also realized by a known technique.

<Preparation of group III nitride crystals>
Next, production of a group III nitride crystal using the production apparatus 10 will be described. Here, a case where an AlN crystal is generated as a group III nitride crystal will be described as an example.

  First, solid Al is placed as a solid source 8 at a predetermined position inside the first reaction tube 1. In addition, an epitaxial substrate obtained by epitaxially growing AlN on a 2-inch sapphire single crystal substrate or a SiC single crystal substrate is placed as a seed crystal 9 at a predetermined position inside the second reaction tube 2.

  In such a state, the first reaction zone 3 is heated to 1000 ° C. by the first heating means 3, and the second reaction zone is heated to 1200 ° C. by the second heating means. The pressure was 15 Torr.

When the first and second reaction zones reach the respective temperatures including the solid source 8 and the seed crystal 9, the HCl gas is supplied from the HCl gas supply source 5 together with the N ₂ gas as the carrier gas as indicated by the arrow AR1. together, NH ₃ from a gas supply source 6, N ₂ gas in company supplied as a carrier gas as shown by an arrow AR3 the NH ₃ gas. The mixing ratio of the reactive gas and the carrier gas supplied from each supply source (reactive gas: carrier gas) is 1:10 and 1: 150, and the total flow rates are 20 sccm and 3000 sccm, respectively.

Under such temperature and gas atmosphere, the reaction between the supplied HCl gas and the solid Al provided as the solid source 8 occurs in the first reaction tube 1, and AlCl is generated as a gas. Since the temperature of the first reaction zone is set to 1000 ° C., AlCl ₃ (monochloride) as a monohalide is preferentially generated instead of AlCl ₃ (trichloride) as a trihalide. Here, since the first reaction tube 1 or at least the inner surface 1s thereof is formed of sapphire, which is an AlCl hardly reactive material, no reaction occurs with the AlCl generated by the reaction. That is, the first reaction tube 1 is not damaged due to the generation of AlCl.

The generated AlCl gas is sent to the second reaction zone as shown by the arrow AR2 in accordance with the flow of the H ₂ gas that is the carrier gas.

At this time, the flow of NH ₃ gas from the first reaction zone toward the second reaction zone as shown by the arrow AR3 exists so as to surround the first reaction tube 1 in the second reaction tube 2. The AlCl gas that has reached the second reaction zone immediately reacts with the NH ₃ gas near the end of the first reaction tube 1 and in the region RE near the first reaction tube 1 in the second reaction zone. Become. That is, AlN as a gas is generated. An arrow AR4 indicates the AlN gas. The NH ₃ gas supply condition is set so that AlCl transported from the first reaction zone is sufficient to be consumed by the reaction with NH ₃ . AlCl hardly remains inside.

  And the AlN produced | generated as gas in this way precipitates sequentially on the seed crystal 9 mounted in the inside of the 2nd reaction tube 2, and an AlN crystal | crystallization is obtained by epitaxially growing. .

As described above, in the present embodiment, AlCl is generated directly to produce a group III nitride crystal, so that it is more efficient than the case where AlCl is generated after the generation of AlCl ₃ once. Group III nitride crystals can be produced.

Even when the second reaction tube 2 is made of quartz, as described above, the AlCl produced in the first reaction tube 1 immediately reacts with NH _{3 when} it reaches the second reaction zone. Since it is used and consumed, the reaction between AlCl and quartz hardly occurs in the second reaction tube 2. Therefore, even when such a configuration is adopted, the production apparatus 10 will not be damaged due to the generation of AlCl, even if the halide is not generated at 700 ° C. or lower.

In addition, the description so far has been directed to the generation of AlN crystals, but for crystal production including other group III elements, the solid source to be used is selected in accordance with the composition of the group III nitride to be produced. Therefore, it can be realized by the same method. In addition, it is desirable to use HCl from the standpoint of gas availability, but a mode in which a halide is generated inside the first reaction tube 1 using another hydrogen halide instead of HCl may be employed. As the carrier gas, it is desirable to use N ₂ gas as a main component from the viewpoint of safety and suppression of etching of the group III nitride material. For example, N ₂ gas such as H ₂ gas or rare gas is used. Other gases can be used.

  Moreover, although the reduced pressure atmosphere is used in the examples, the time to reach the seed crystal from the raw material mixing part can be shortened, which is a preferable atmosphere in the present invention. In the absence of a reduced-pressure atmosphere, particularly when a group III nitride containing Al is generated, the polymerization reaction of the intermediate product generated around the region RE, which is at a high temperature, proceeds too much to generate a group III nitride powder. This is because there is a possibility that the crystal quality of the target group III nitride crystal is deteriorated and the film forming efficiency is lowered. In order to avoid the occurrence of such a state, it is desirable to set the pressure so that the arrival time of the raw material gas from the raw material mixing portion to the seed crystal is 0.1 seconds or less. This is because if the arrival time of the source gas is 0.1 second or less, the polymerization reaction of the intermediate product is sufficiently suppressed, and the film formation efficiency is hardly lowered.

  As described above, according to the present embodiment, even if the reaction between the solid source of the group III nitride containing Al and the hydrogen halide is performed at a temperature of 700 ° C. or higher, it is damaged in the manufacturing process. It is possible to provide a device for producing a group III nitride having no crystal.

<Modification>
FIG. 2 is a schematic cross-sectional view schematically showing the structure of a Group III nitride crystal manufacturing apparatus 20 as a modification of the manufacturing apparatus 10 according to the above-described embodiment. Similar to the manufacturing apparatus 10, the manufacturing apparatus 20 includes a first reaction tube 11, a second reaction tube 12, a first heating unit 13, a second heating unit 14, an HCl gas supply source 15, and an NH ₃ gas. It is mainly composed of a supply source 16 and an exhaust means 17.

In the production apparatus 20, the second reaction tube 12 has a double structure of an inner reaction tube 12a and an outer reaction tube 12b, and the NH ₃ gas supply source 16 is connected to the inner reaction tube 12a. Except for this point, the configuration of the manufacturing apparatus 20 is almost the same as the configuration of the manufacturing apparatus 10, and the operation of each unit is also common. That is, the first reaction tube 11 or at least the inner surface 11s thereof is formed of a material that is hardly reactive to AlCl, and the solid source 18 can be placed inside the first reaction tube 1. . In the second reaction tube 12, the seed crystal 19 can be placed on the outer reaction tube 12b. Furthermore, each of the first heating means 13 and the second heating means 14 is provided so as to surround the second reaction tube 12, and the first reaction zone and the second reaction zone are also similar to the production apparatus 10. It is defined similarly. Note that the second reaction tube 12 can also be formed of, for example, quartz.

In such a manufacturing apparatus 20, even when solid Al is used as the solid source 18 as in the above embodiment, if the temperature of the first reaction zone is 1000 ° C., AlCl gas is generated inside the first reaction tube 11. in it is generated, the AlCl gas is not able to react with the first reaction tube 11 immediately reacts AlN is generated around the NH ₃ gas and a region RE 'to be supplied from the NH ₃ gas supply source 16 Will do.

Also in this case, the NH ₃ gas supply condition is set so that the AlCl transported from the first reaction zone is sufficient to be consumed by the reaction with NH ₃ . AlCl hardly remains inside, and AlN produced as a gas is sequentially deposited on the seed crystal 19 and epitaxially grows.

  Therefore, the production apparatus 20 can also produce a group III nitride crystal efficiently as in the production apparatus 10 according to the above-described embodiment.

1 is a schematic cross-sectional view schematically showing the structure of a Group III nitride crystal production apparatus 10 according to an embodiment of the present invention. It is a cross-sectional schematic diagram which shows roughly the structure of the production apparatus 20 of the group III nitride crystal based on the modification of this invention.

Explanation of symbols

1, 11 First reaction tube 1s, 11s (first reaction tube) inner surface 2, 12 Second reaction tube 3, 13 First heating means 4, 14 Second heating means 5, 15 HCl gas supply source 6, 16 NH ₃ Gas supply source 7, 17 Exhaust means 8, 18 Solid source 9, 19 Seed crystal 10, 20 Production device 12a Inner reaction tube 12b Outer reaction tube RE, RE '(Group III nitride reacts and generates) region

Claims (9)

An apparatus for producing a group III nitride crystal,
A first reaction tube for internally reacting with a group III element solid and a hydrogen halide provided from a predetermined source to form a group III element halide;
It is in spatial communication with the first reaction tube, and a group III nitride is generated by reacting the halide and a nitrogen element-containing gas provided from a predetermined supply source in a gas phase. A second reaction tube for depositing nitride on a predetermined seed crystal;
With
At least an inner surface of the first reaction tube is formed of a hardly-reactive substance with respect to a monohalide of the group III element,
An apparatus for producing a group III nitride crystal characterized by the above. The manufacturing apparatus according to claim 1,
Inserted into the second reaction tube with one end of the first reaction tube open,
In the second reaction tube, the nitrogen element-containing gas is supplied so that the flow of the nitrogen element-containing gas surrounds the one end.
An apparatus for producing a group III nitride crystal characterized by the above. A method for producing a group III nitride crystal containing Al element,
A first reaction step of reacting with a solid source of a group III element containing at least solid Al and a hydrogen halide provided from a predetermined source to form a group III element halide;
A second reaction step of generating a group III nitride by performing a gas phase reaction between the halide and a nitrogen-containing gas supplied from a predetermined source;
A precipitation step of depositing the group III nitride on a predetermined seed crystal;
With
The first reaction step is performed inside a first reaction tube having at least an inner surface formed of a hardly-reactive substance with respect to Al monohalide;
A method for producing a group III nitride crystal containing an Al element. A manufacturing method according to claim 3,
Inserted into the second reaction tube with one end of the first reaction tube open,
Performing the second reaction step while supplying the nitrogen element-containing gas so that the flow of the nitrogen element-containing gas surrounds the one end inside the second reaction tube;
A method for producing a group III nitride crystal containing an Al element. A manufacturing method according to claim 3 or claim 4, wherein
An epitaxial substrate formed by epitaxially growing a group III nitride having a content ratio of Al element equal to or higher than the content ratio of Al element in the group III nitride to be produced is used as the predetermined seed crystal.
A method for producing a group III nitride crystal containing an Al element. A manufacturing method according to claim 5,
An epitaxial substrate obtained by epitaxially growing AlN is used as the predetermined seed crystal.
A method for producing a group III nitride crystal containing an Al element. A manufacturing method according to any one of claims 3 to 6,
The first reaction step is performed in a temperature range that generates a monohalide as the halide.
A method for producing a group III nitride crystal containing an Al element.   3. The Group III nitride crystal containing Al produced by using the mixture of Group III element solids containing at least Al as the Group III element solids in the production apparatus according to claim 1 or 2. A group III nitride crystal containing an Al element, produced by the production method according to claim 3.

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