JP7138561B2 - Vapor phase growth apparatus and method for producing group III nitride single crystal - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vapor phase growth apparatus and a method for producing a Group III nitride single crystal using the vapor phase growth apparatus. More specifically, the present invention relates to a vapor phase growth apparatus capable of stably producing high-quality group III nitride single crystals and a method for producing group III nitride single crystals using the vapor phase growth apparatus.

Group III nitride semiconductors such as aluminum nitride, gallium nitride, and indium nitride can be mixed crystal semiconductors of any composition, and the bandgap value can be changed depending on the composition of the mixed crystal. Therefore, by using a group III nitride semiconductor crystal, in principle, it is possible to manufacture a wide range of light-emitting devices from infrared light to ultraviolet light. In particular, in recent years, the development of light-emitting devices using aluminum-based group III nitride semiconductors (mainly aluminum gallium nitride mixed crystals) has been vigorously pursued.

Examples of the method for producing the group III nitride single crystal substrate include a sublimation (PVT: Physical Vapor Transport) method, a metal organic chemical vapor deposition (MOCVD) method, and a hydride vapor phase epitaxy (HVPE: Hydride Vapor Phase Epitaxy) method. ) method is known. The PVT method is a method for growing a group III nitride single crystal by sublimating a solid group III nitride at a high temperature and precipitating it on a low-temperature base substrate. There is an advantage that a thick film can be grown at a high growth rate. On the other hand, the MOCVD method and the HVPE method are methods of producing a single crystal by reacting a Group III source gas (eg, aluminum chloride gas, etc.) and a nitrogen source gas (eg, ammonia gas, etc.) on a base substrate. be.

A problem with the vapor phase growth method is the contamination of the base substrate surface or the Group III nitride single crystal layer with foreign matter. If crystal growth is performed with foreign matter adhering to the crystal growth surface, crystal growth abnormalities around the adhering foreign matter will cause crystal defects and abnormal thickness of the growth layer, and will be stacked on the group III nitride single crystal layer. It is known that it causes deterioration in performance such as reduction in luminous efficiency in a light-emitting element that is used. Furthermore, the location where the foreign matter adheres has a significantly lower mechanical strength than other regions, and not only forms pits (dents) during polishing, but also cuts into chip shapes after laminating the light emitting element layer. It is also known that the substrate tends to become a starting point of cracks during processing and causes a significant decrease in the yield of light-emitting devices manufactured using the substrate. Therefore, it is desired to reduce the contamination as much as possible during the production of the Group III nitride single crystal laminate.

Here, it is believed that the main cause of contamination by foreign matter is adherence of solid particles such as group III nitrides and group III metals, which are produced by-products during the transportation or reaction of the raw material gas, to the base substrate. Various methods have been proposed for growing crystals while preventing the formation of solid particles. For example, as a method for producing an aluminum nitride single crystal, an aluminum halide gas as a raw material gas and a nitrogen source gas are reacted in the presence of a halogen-based gas such as hydrogen chloride gas to obtain an equilibrium partial pressure of an aluminum monohalide gas. A method for producing a single crystal by significantly lowering the A method for producing a high-quality single crystal (see Patent Document 2), a method for reducing crystal defects observed as bright spots by reflection X-ray topography by supplying a halogen-based gas before supplying a raw material gas (see Patent Document 2). See Patent Documents 3 and 4), etc. are known. By the above method, contamination by foreign substances and side reactions in the vapor phase epitaxy can be suppressed to some extent, and a high-quality Group III nitride single crystal layer can be produced.

JP 2015-017030 International publication WO2014/031119 JP 2016-216342 International publication WO2016/076270

In the vapor phase growth apparatus, the raw material gas is consumed by crystal growth on the seed substrate in the growth section, and by parasitic reactions in the vapor phase and on the walls of the members constituting the reaction tube for vapor phase growth. However, the raw material gas supplied to the reaction is a part of the raw material gas supplied to the reaction tube, and most of the raw material gas is exhausted as it is.

Exhaust gas emitted during the vapor phase growth reaction is sent to an exhaust gas treatment device such as a wet scrubber connected to the vapor phase growth apparatus, and the exhaust gas treatment device absorbs harmful components such as raw material gases in the exhaust gas. It is common to have a configuration that abolishes harm by

However, depending on the growth conditions of the group III nitride single crystal, the exhaust gas may not be sufficiently detoxified in the exhaust gas treatment apparatus and may be exhausted into the atmosphere, or in the exhaust pipe leading from the reaction tube to the exhaust gas treatment apparatus. The study by the present inventors has revealed that the exhaust pipe may be clogged during the growth of the group III nitride single crystal layer due to solid precipitation. It was also found that when clogging occurs, growth cannot be continued for a longer period of time due to an increase in pressure, and in addition, backflow of exhaust gas may cause foreign matter to enter the group III nitride single crystal. rice field.

Accordingly, an object of the present invention is to solve the problem of exhaust gas abatement in an exhaust gas treatment device and the problem of clogging due to deposition of solids in the exhaust pipe, and to stably produce a high-quality group III nitride single crystal layer. It is an object of the present invention to provide a vapor phase epitaxial growth apparatus and a method for producing a Group III nitride single crystal using the vapor phase epitaxial growth apparatus.

The present inventors conducted studies to solve the above problems. The composition of the exhaust gas discharged from a reaction tube for growing a group III nitride single crystal using a group III halide gas and an ammonia gas and the composition of a solid precipitated when these gases are cooled were determined by thermodynamic analysis. . As a result, it was found that the exhaust gas mainly contained group III halide gas, ammonia gas, hydrogen halide gas and carrier gas. It was also found that the precipitates upon cooling mainly contained group III nitrides, ammonium halides and group III halides. It was also found that their composition changes depending on the supply flow rates of the raw material gas and carrier gas and the cooling temperature. Furthermore, analysis of the reaction that occurs when these gases or precipitates are supplied to a wet scrubber, which is an exhaust gas treatment device, revealed that gaseous or solid group III halides such as gallium chloride and aluminum chloride are contained in the scrubber. It was presumed that hydrogen chloride was generated by a violent exothermic reaction when it came into contact with water, and there was concern about the load on the exhaust gas treatment equipment due to heat generation. Since the inside of the exhaust gas treatment apparatus is usually at room temperature, group III halides are hardly supplied in the gaseous state into the exhaust gas treatment apparatus, but group III halides precipitated in the pipe leading to the exhaust gas treatment apparatus It is conceivable that the solids may be supplied into the exhaust gas treatment apparatus along with the air current. From these facts, it was speculated that the problem of exhaust gas abatement and concern about the load on the exhaust gas treatment apparatus were mainly caused by group III halides. It was also speculated that the clogging problem was due to relatively low density group III halides and ammonium halides rather than group III nitrides. Therefore, from the reaction tube for growing the group III nitride single crystal to the exhaust gas treatment apparatus, the group III halide gas in the exhaust gas discharged from the reaction tube, and the halogen-based gas and ammonium which are the raw materials of the ammonium halide The inventors have found that the above problems can be solved by collecting any component of the gas, and have completed the present invention.

That is, the first invention provides a growth section having a growth section reaction zone for growing a group III nitride single crystal on a substrate by reacting a group III source gas and a nitrogen source gas, and a gas that has passed through the growth section. A vapor phase growth apparatus comprising a discharge section for discharging
The discharge unit includes a collection unit that collects at least one component of the exhaust gas that has passed through the growth unit, and an exhaust gas treatment device that collects at least one component in the exhaust gas that has passed through the collection unit,
The group III source gas is an aluminum halide gas, the nitrogen source gas is ammonia gas, the group III nitride single crystal is an aluminum nitride single crystal,
The exhaust gas contains aluminum chloride gas and hydrogen chloride gas,
Between the growth section and the collection section,
an exhaust gas reaction zone for supplying ammonia gas that reacts with the hydrogen chloride gas out of the exhaust gas that has passed through the growth section, and causing the hydrogen chloride gas component in the exhaust gas that has passed through the growth section to react with the ammonia gas; has
The exhaust gas reaction zone is connected to the growth section by a first exhaust gas supply pipe and is connected to the trapping section by a second exhaust gas supply pipe . having a plurality of gas supply ports,
The second exhaust gas supply pipe has a length of 10 cm or more and 2 m or less,
The collecting unit is equipped with a filter and an external cooling device to collect aluminum chloride and ammonium chloride ,
The exhaust gas treatment device includes a collection liquid containing water,
In the vapor phase growth apparatus, the temperature of the collection part is set to 190° C. or less.

It is preferable that the vapor phase growth apparatus of the present invention take the following aspects.
It is preferable that the outlet reaction zone includes an ammonia gas supply pipe having a plurality of the ammonia gas supply ports .
a reaction tube in which the growth section has a growth section reaction zone for growing a group III nitride single crystal on a substrate by reacting the group III source gas and the nitrogen source gas;
a holding table disposed in the reaction zone of the growth section and holding a substrate;
a group III source gas supply nozzle for supplying a group III source gas to the reaction zone;
a nitrogen source gas supply nozzle for supplying the nitrogen source gas to the growth zone reaction zone;
Furthermore, it is preferable to have a structure in which at least one type of halogen-based gas selected from hydrogen halide gas and halogen gas is supplied to the growth zone reaction zone.

In the second aspect of the present invention, the above- described Having a step of reacting the group III source gas and the nitrogen source gas,
In the process, at least one halogen-based gas selected from a hydrogen halide gas and a halogen gas is supplied to the reaction zone of the growth section, in the method for producing an aluminum nitride single crystal which is a Group III nitride single crystal.

The vapor phase growth apparatus of the present invention removes gallium chloride gas and chloride contained in the exhaust gas emitted from the production of a group III nitride single crystal by the vapor phase growth method, before treating the gas with the exhaust gas treatment apparatus. It is characterized by the provision of a collecting section for previously collecting group III halide gas such as aluminum gas, or halogen-based gas or ammonia gas as raw materials for deposition of ammonium halide. By adopting such a structure, it is possible to suppress the inflow of group III halides into the exhaust gas treatment apparatus, suppress the reaction between water in the exhaust gas treatment apparatus and the group III halides, and suppress the exhaust gas in the exhaust gas treatment apparatus. and the problem of clogging due to the precipitation of group III halides and ammonium halides in the exhaust pipe can be solved, and high-quality group III nitride single crystals can be produced stably. is.

In particular, when a group III nitride single crystal is produced by the method described in Patent Document 1, in which a group III nitride single crystal is grown in the coexistence of a halogen-based gas, a large amount of the group III halide gas is contained in the exhaust gas. When this method is adopted, it is possible to stably produce a high-quality Group III nitride single crystal by using the vapor phase growth apparatus of the present invention.

The present inventors presume the reason why the vapor phase growth apparatus of the present invention can solve the above problems as follows. As the gas to be supplied to the growth section, when there is little ammonia gas (for example, when equimolar group III halide gas and ammonia gas are used) or when there is much hydrogen chloride gas (for example, as in Patent Document 1, halogen-based gas is supplied to the exhaust gas treatment device), the gas supplied to the exhaust gas treatment apparatus is a mixed gas of group III halide gas, hydrogen chloride gas, and carrier gas (for example, hydrogen). These gases are treated in an exhaust gas treatment system, but when group III halides come into contact with water in an exhaust gas treatment system such as a scrubber, they react violently to generate hydrogen chloride. It is presumed that the absorption and detoxification cannot be carried out sufficiently, and it is exhausted into the atmosphere. Therefore, group III halides are collected from the gas discharged from the reaction zone of the growth section before being treated by the exhaust gas treatment apparatus, thereby allowing the group III halides to flow into the exhaust gas treatment apparatus and in the exhaust pipe. It is presumed that the above problem can be solved because clogging by group III halides can be suppressed. On the other hand, when the gas supplied to the growth section is more ammonia gas than the group III halide gas, in the growth section, the group III halide gas reacts with the ammonia gas to produce the target group III nitriding gas. Hydrogen chloride gas is produced as a by-product. Here, since the ammonia gas is excessive with respect to the group III halide gas supplied to the growth zone reaction zone, the by-produced hydrogen chloride gas reacts with the remaining ammonia gas to become solid ammonium chloride, resulting in clogging. cause. Therefore, in the present invention, by collecting hydrogen chloride gas or ammonia gas, which is a raw material of ammonium chloride, in the collection unit, deposition of ammonium chloride in the exhaust pipe can be suppressed and clogging can be suppressed. It is assumed that it is possible to solve the above problems. Therefore, it is presumed that clogging can be suppressed under any Group III nitride single crystal growth conditions.

1 is a schematic diagram of an example of a vapor phase growth apparatus of the present invention; FIG. 1 is a schematic diagram of an example of a growth section that is a part of the vapor phase growth apparatus of the present invention; FIG. It is a schematic diagram explaining the aspect which supplies halogen-type gas from a III group source gas nozzle. It is a schematic diagram explaining the aspect which supplies a halogen-type gas from a nitrogen source gas nozzle. 1 is a schematic diagram of an example of an exhaust section which is a part of the vapor phase growth apparatus of the present invention; FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the forms shown below are examples of the present invention, and the present invention is not limited to these forms.

<I. Vapor-phase growth apparatus of the present invention>
A vapor phase growth apparatus according to a first aspect of the present invention will be described. FIG. 1 is a schematic diagram of the structure of the vapor phase growth apparatus of the present invention. As shown in FIG. 1, the vapor phase growth apparatus 100 of the present invention is composed of a growth section 200 and an exhaust section 300, and the exhaust section 300 is composed of a collection section 340 and an exhaust gas processing apparatus 360. It is a feature. The growing section 200 and the collection section 340, and the collection section 340 and the exhaust gas treatment device 360 are connected by exhaust gas supply pipes 311 and 350, respectively. Exhaust gas discharged from the growing section 200 is introduced into the collection section 340 through the exhaust gas supply pipe 311, and at least one component in the exhaust gas is collected in the collection section 340. FIG. The exhaust gas that has passed through the collection unit 340 is introduced into an exhaust gas treatment device 360 through an exhaust gas supply pipe 350, where other components in the exhaust gas are collected and discharged outside the system. Each component of the vapor phase growth apparatus of the present invention will be described in detail below.

<Growing part>
The growth section 200 is an apparatus for growing a group III nitride single crystal on a substrate by reacting a group III source gas and a nitrogen source gas. FIG. 2 is a schematic diagram showing an example of the growing part 200. As shown in FIG. The growth section 200 has a substrate holder 203 that holds a substrate (base substrate) 220 on which the group III nitride single crystal is grown, and a reaction tube 202 that has a growth section reaction zone 201 on which the group III nitride single crystal is grown. , a group III source gas supply nozzle 211 that supplies the group III source gas to the growth section reaction zone 201 , and a nitrogen source gas supply nozzle 210 that supplies the nitrogen source gas to the growth section reaction zone 201 .

It suppresses turbulence in the gas flow of the group III source gas and the nitrogen source gas supplied onto the substrate 220 held on the substrate holding table 203, and efficiently discharges exhaust gas that has passed through the reaction zone 201 of the growth section. From this point of view, the exhaust gas supply pipe 311 is preferably provided on the side opposite to the group III source gas supply nozzle 211 and the nitrogen source gas supply nozzle 210 with respect to the substrate holding table 203 , that is, on the downstream side of the substrate holding table 203 .

The substrate holding table 203 in the growth section 200 may include a mechanism (not shown in FIG. 2) for rotating the substrate 220 held on the holding table during growth of the group III nitride single crystal. A heating means 204 may be provided for heating the substrate holding table 203 and heating the substrate 220 by heat transfer from the holding table. Specific examples of the heating means 204 include known heating means such as a heating means using a high-frequency coil and a resistance heater.

Further, an external heating means 205 for heating the reaction tube 202 to heat the reaction zone 201 in the reaction tube 202 can be provided.

Further, in the growth zone reaction zone 201, in addition to the Group III raw material gas and the nitrogen source gas, at least one halogen-based gas selected from hydrogen halide gas and halogen gas (hereinafter also simply referred to as "halogen-based gas") is supplied. You may have a means to supply. As a means for supplying the halogen-based gas, as shown in FIG. 2, a halogen-based gas supply nozzle 212 may be installed and supplied from the nozzle. Alternatively, as shown in FIG. 3, the halogen gas is placed at an arbitrary position from the group III source gas supply nozzle outlet, which is one end of the group III source gas supply nozzle 211, to the source portion, which is the other end, of the group III source gas supply nozzle 211. for supplying at least one halogen-based gas selected from hydrogen chloride gas and halogen gas (hereinafter, the halogen-based gas added to this group III raw material gas may be referred to as "group III additional halogen-based gas"); An additional halogen-based gas supply nozzle may be installed, and the group III source gas and the additional group III halogen-based gas may be merged in the group III source gas supply nozzle 211 .

Alternatively, as shown in FIG. 4, at an arbitrary position of the nitrogen source gas supply nozzle 210, at least one halogen-based gas selected from the hydrogen halide gas and the halogen gas (hereinafter referred to as a halogen-based gas added to the nitrogen source gas) (sometimes referred to as "nitrogen source added halogen-based gas") is installed, and the nitrogen source gas and the group III added halogen-based gas are supplied in the nitrogen source gas supply nozzle 210. may merge. A structure in which a halogen-based gas is not supplied may be employed, but in the present invention, a structure in which a halogen-based gas is supplied is employed, and is particularly effective when crystal growth is performed under conditions in which a halogen-based gas is supplied during crystal growth. .

Using the vapor phase growth apparatus of the present invention, for example, a group III halide gas (eg, aluminum chloride gas, gallium chloride gas, etc.) is used as the group III source gas supplied from the group III source gas supply nozzle 211, and nitrogen source gas A group III nitride single crystal can be grown by the HVPE method using ammonia gas as the nitrogen source gas supplied from the supply nozzle 210 . The gas that has passed through the growth section reaction zone 201 is discharged to the outside of the growth section 200 through an exhaust gas supply pipe 311 . As the group III source gas, in addition to group III halide gas, group III organometallic compound gas (e.g., trimethylaluminum gas, trimethylgallium gas, etc.) and group III metal gas (e.g., aluminum gas, gallium gas, etc.) can be used. can also The case of the HVPE method using group III halide gas will be described below.

A group III halide gas, which is a group III source gas, can be generated in a source section (not shown) provided upstream of the group III source gas supply nozzle 211 . For example, group III halide gas (eg, aluminum chloride gas, gallium chloride gas, etc.) is generated by supplying a halogen-based gas (eg, hydrogen chloride gas, chlorine gas, etc.) to the group III metal placed in the raw material section. In order to proceed with this production reaction, the raw material is heated at a temperature suitable for the reaction (for example, in the generation of aluminum chloride gas, it is usually about 150 to 1000 ° C., preferably about 300 to 660 ° C., more preferably about 300 to 600 ° C. and in the generation of gallium chloride gas, it is usually heated to about 300 to 1000° C.) In addition, a solid group III halide is placed in the raw material section and heated to sublime it. Group III halide gases can also be generated at .

A group III halide gas (group III source gas) is led to the growth section reaction zone 201 in the reaction tube 202 by a group III source gas supply nozzle 211 . The group III source gas supply nozzle 211 is arranged to blow out a group III halide gas (group III source gas) from the upper side of the substrate holding table 203 toward the upper side of the substrate holding table 203 .

Materials constituting the group III raw material gas supply nozzle 211 or the additional halogen-based gas supply nozzle for supplying the group III additional halogen-based gas include heat-resistant glass, quartz glass, alumina, zirconia, stainless steel, and inconel. Corrosion-resistant alloys and the like can be exemplified, among which quartz glass can be preferably used.

The nitrogen source gas supply nozzle 210 is arranged so as to blow out the nitrogen source gas from above the outlet of the group III source gas supply nozzle 211 toward above the substrate holding table 203 . By disposing the outlet of the nitrogen source gas supply nozzle 210 above the outlet of the group III source gas supply nozzle 211, the nitrogen source gas (nitrogen source gas) can be uniformly supplied onto the substrate holding table 203. It is preferable because Further, when ammonia gas is used as the nitrogen source gas, ammonia gas diffuses relatively easily. Therefore, the outlet of the nitrogen source gas supply nozzle 210 is arranged below the outlet of the group III raw material gas supply nozzle 211. You may Materials for constituting the nitrogen source gas supply nozzle 210 or the additional halogen-based gas supply nozzle for supplying the nitrogen source additional halogen-based gas include heat-resistant glass, quartz glass, alumina, zirconia, stainless steel, and heat-resistant materials such as Inconel. Corrosive alloys and the like can be exemplified, among which quartz glass can be preferably used.

The group III source gas supplied from the group III source gas supply nozzle 211 and the nitrogen source gas supplied from the nitrogen source gas 210 react in the growth section reaction zone 201 in the growth section, whereby a A group III nitride single crystal is grown on the substrate 220 placed on the . In order to advance this reaction, the substrate 220 is kept at a temperature suitable for the reaction (for example, in the case of growing an aluminum nitride single crystal, it is usually about 1000 to 1700° C., preferably about 1200 to 1700° C., more preferably about 1350 to 1650° C.). , which is usually about 800 to 1100° C. in the growth of gallium nitride single crystal). As a means for heating the substrate, a heating means 204 for heating the substrate 220 by heating the substrate holder 203 and heat transfer from the holder may be used. Alternatively, a means for heating the entire reaction tube 202 may be used. The heating means 204 and the external heating device 205 may be used alone or in combination.

Since the reaction tube 202 has the growth part reaction zone 201 inside, it is preferably made of a heat-resistant and acid-resistant nonmetallic material such as quartz glass, alumina, sapphire, heat-resistant glass, or the like. An outer chamber (not shown) may be provided around the outer circumference of the reaction tube 202 . The outer chamber may be made of the same material as the reaction tube 202, but since the outer chamber is not in direct contact with the growth reaction zone 201, it should be made of a general metal material such as stainless steel. is also possible.

Further, for example, when a mixed crystal is grown by the HVPE method, a plurality of types of Group III metal raw materials are arranged in a raw material section reactor (not shown), and a group III halide mixed gas is generated by supplying a halide gas. , it is also possible to introduce the mixed gas into the growth zone reaction zone 201 through the group III source gas supply nozzle 211 . On the other hand, the raw material section reactor is configured so that no group III metal raw material is arranged, that is, a group III halide mixed gas is separately generated without reacting the halide gas and the group III metal, and the It is also possible to adopt a raw material section reactor in which the mixed gas is heated to a desired temperature (for example, 150 to 1000° C.) by a heating device and supplied as a Group III raw material gas.

In the above description of the present invention, the vapor phase growth apparatus 100 in which the group III source gas supply nozzle 211 single pipe is present inside the growth zone reaction zone 201 was exemplified, but the present invention is not limited to this form. For example, a barrier gas channel (not shown) is formed outside the group III source gas channel so as to cover the outer circumference of the group III source gas supply nozzle 211, and surrounds the outlet of the group III source gas supply nozzle. A barrier gas outlet may be formed. As the barrier gas, for example, gases commonly used as barrier gases such as hydrogen, nitrogen, argon, and helium can be used without particular limitation. The barrier gas makes it possible to control the position where the group III source gas and the nitrogen source gas mix in the growth zone reaction zone 201, and also prevents mixing and reaction of the nitrogen source gas and the group III source gas at unintended positions. Since it is possible to prevent it in advance, it is possible to greatly reduce deposits on the nozzle. In addition, the axis of the group III source gas supply nozzle 211 (central position in the height direction of the nozzle) is offset in the height direction with respect to the axis of the barrier gas nozzle within a range that does not adversely affect the crystal growth ( offset).

Also, the vapor phase growth apparatus 100 may have a structure for supplying a pushing gas. That is, the pushing gas is supplied to the reaction tube 202 so that the group III raw material gas, the nitrogen source gas, and the barrier gas uniformly flow to the side where the exhaust gas supply pipe 311 is provided without backflow in the reaction tube 202. A push gas inlet port (not shown) may be provided for introducing into. Usual gases such as hydrogen, nitrogen, argon, and helium can be used as the pushing gas. Further, the inside of the reaction tube 202 is decompressed so that the group III source gas, the nitrogen source gas, and the barrier gas uniformly flow to the side where the exhaust gas supply pipe 311 is provided without backflowing in the reaction tube 202. Backflow of the gas flow inside the reaction tube 202 may be suppressed by providing an exhaust mechanism (not shown) in the exhaust portion. It is preferable that the mechanism for evacuating under reduced pressure is arranged between the collection section and the exhaust gas treatment device. The pressure inside the reaction tube 202 is selected within a range that does not adversely affect crystal growth. The pressure inside the reaction tube 202 is usually 0.1 to 1.5 atm, generally 0.2 atm to atmospheric pressure.

The cross-sectional shape of the outlet of the nitrogen source gas supply nozzle 210 and the outlet of the group III source gas supply nozzle 211 is not particularly limited, and may be circular, elliptical, rectangular, or the like depending on the size of the substrate to be supplied. It is possible to select the shape to

<Discharge part>
The discharge unit 300 will be described below. The discharge section 300 is provided for the purpose of performing processing for discharging the exhaust gas supplied from the growth section 200 into the atmosphere. FIG. 5 is a schematic diagram showing an example of the discharge section 300. As shown in FIG.

The exhaust gas supply pipe 311 is connected to the downstream side of the growth section 200 ( FIG. 2 ), and the gas in the growth section reaction zone 201 is supplied to the collection section 340 through the exhaust gas supply pipe 311 . The collection section 340 collects at least one component in the gas that has passed through the growth section. In addition, the exhaust gas that has passed through the collection unit 340 is supplied to the exhaust gas treatment device 360 through the exhaust gas supply pipe 350, and other components in the exhaust gas are collected in the exhaust gas treatment device 360 and released outside the system. Ejected.

The exhaust gas supply pipe 311 can be at a temperature that follows the effects of heating the growth zone, but it is also possible to control the temperature of the exhaust gas supply pipe 311 by an external heating means or an external cooling means 312. can. As described above, at least one component in the gas that has passed through the growth section is collected by the collection section 340, but may precipitate in the exhaust gas supply pipe 311 depending on the temperature and structure of the discharge section 300. In the present invention, it is preferable that solid deposition occurs in the collection section 340 in order to suppress clogging due to deposition in the discharge section. Therefore, it is preferable to set the temperature of the exhaust gas supply pipe 311 to a temperature at which solids do not precipitate. However, the inventors have found that if the temperature is higher than the temperature of the growth reaction zone 201 , the gas may flow back from the exhaust gas supply pipe 311 to the growth reaction zone 201 . This phenomenon occurs not only during the growth of the group III nitride single crystal, but also during the temperature rise or fall of the growing portion, or while the growing portion is not heated. Therefore, it is preferable to keep the temperature of the exhaust gas supply pipe 311 below the temperature of the growth reaction zone 201 . Therefore, it is preferable to adjust the temperature appropriately by the external heating means or external cooling means 312 . Specifically, the temperature of the exhaust gas supply pipe 311 during growth is preferably 50° C. or higher and 400° C. or lower, and more preferably 50° C. or higher and 300° C. or lower.

The means for collecting at least one component in the exhaust gas in the collecting section 340 may be appropriately selected according to the properties of the component to be collected. In FIG. 5, a filter 341 is shown as a means for collecting solid content, but the collecting part 340 is filled with a solvent such as water or an organic solvent that dissolves the collected components, and exhaust gas is passed through the solvent. At least one component in the exhaust gas may be dissolved in the solvent and collected. Among these means, a method using a mesh-like filter that allows only gas to pass through but does not allow solids to pass through is preferably employed. Solid ammonium chloride and aluminum chloride to be collected are usually in the form of powder, depending on the temperature and the surrounding gas atmosphere. Therefore, the filtration accuracy of the filter is preferably 1-500 μm, more preferably 10-300 μm.

Furthermore, depending on the components in the exhaust gas, if the exhaust unit 300 is composed only of the exhaust gas supply pipe 311 and the collecting unit 340, the collecting unit 340 may not sufficiently collect them. . For this reason, a reactive gas that reacts with one component in the exhaust gas is supplied before being collected in the collecting unit 340, and the component in the exhaust gas that has passed through the growth unit 200 and the reactive gas are combined. After reacting, the product may be collected by the collection unit 340 . In FIG. 5, a space in which the exhaust gas reacts with the reactive gas, that is, the exhaust reaction zone 320 is installed in front of the collector 340, and the reactive gas for supplying the reactive gas to the exhaust reaction zone 320 is installed. A supply pipe 321 is installed. A reactive gas is supplied to the exhaust reaction zone 320 from a reactive gas supply port 322 in a reactive gas supply pipe 321, and reacts with at least one component in the exhaust gas by contact between the exhaust gas and the reactive gas. The discharge section reaction zone 320 may be located between the growth section 200 and the collection section 340 or at least in the collection section 340 . A reactive gas supply port 322 may be provided in the exhaust gas supply pipe 311 and the inside of the exhaust gas supply pipe 311 may be used as the exhaust reaction zone 320, or the reactive gas supply pipe 321 may be installed in the collection unit 340 to The inside of the collecting section 340 may be used as the discharging section reaction zone 320 . From the viewpoint of efficiently reacting at least one component in the exhaust gas with the reactive gas, it is preferable to have a structure in which the exhaust reaction zone 320 is provided between the growth section 200 and the collection section 340 . In this case, the exhaust reaction zone 320 and the collector 340 are connected by the exhaust gas supply pipe 330 . In addition, in order to suppress precipitation in the exhaust gas supply pipe 330 of a reaction product that has reacted with at least one component in the exhaust gas in the exhaust reaction zone 320, the exhaust gas is heated by an external heating means or an external cooling means 331. It is preferable to appropriately adjust the temperature in the supply pipe 330 .

The collecting section 340 is preferably cooled by an external cooling means 342 in order to reliably collect the reaction product.

Further, as the exhaust gas treatment device 360, a means such as a scrubber, etc., for absorbing the exhaust gas in a collecting liquid and collecting the components in the gas can be adopted. The components of the gas supplied to the exhaust gas treatment device 360 are mainly the unreacted portion of the reactive gas supplied to the exhaust reaction zone 320 in addition to the carrier gas such as nitrogen gas and hydrogen gas. A collection liquid in which the reactive gas has a high solubility is circulated in the exhaust gas treatment device 360, and the reactive gas can be collected by bringing the reactive gas into contact with the collection liquid. The collecting liquid may be water, an acidic aqueous solution, a basic aqueous solution, or an organic solvent. Alternatively, by supplying a second reactive gas that reacts with the reactive gas as in the exhaust reaction zone 320, not only dissolution in the collected liquid in the exhaust gas treatment device 360 but also the solvent Neutralization reactions can also occur. For example, ammonia gas is supplied to the discharge section reaction zone 320 in order to collect the hydrogen chloride gas supplied from the growth section 200 in the collection section 340, and the unreacted portion of the ammonia gas is collected in the exhaust gas processing device 360. Hydrogen chloride gas can be supplied to the exhaust gas treatment device 360 for this purpose. The hydrogen chloride gas is supplied to the growth section 200 after a hydrogen chloride gas bypass pipe (opening the gas cylinder) is provided separately from the group III source gas supply nozzle 211 and the halogen-based gas supply nozzle 212 of the vapor phase growth apparatus, for example. By directly connecting the piping for circulating the gas until the gas supply to the growing part 200 is stopped and the piping for circulating the gas until the gas cylinder is closed after the supply to the growing part 200 is stopped, the exhaust gas processing device 360 can be Hydrogen chloride gas can be supplied without waste. At this time, if the amount of collected liquid is small or the distance between the supply port of the exhaust gas supply pipe 350 and the supply port of the second reactive gas supply pipe is short, precipitation will occur in the gas phase or on the wall surface of the exhaust gas treatment device 360. Therefore, it is preferable to maintain a sufficient amount of collected liquid and a sufficient distance between the supply ports of both pipes. Stainless steel, quartz glass, vinyl chloride, or the like is used for the piping constituting the discharge part 300, but it is preferable to use stainless steel from the viewpoint of strength.

<Method of collecting exhaust gas>
A method for collecting components in the exhaust gas in the case of the HVPE method using group III halide gas will be described below.

Exhaust gas discharged from the growth unit 200 may contain push-out gas such as hydrogen gas or nitrogen gas, unreacted group III raw material gas, unreacted nitrogen source gas, and by-produced halogen-based gas. be. Furthermore, when a halogen-based gas is supplied to the reaction zone 201 of the growing part, it is considered that the halogen-based gas is also present. For example, when gallium monochloride gas is used as the group III source gas and ammonia gas is used as the nitrogen source gas to grow a gallium nitride single crystal, in the growth section, GaCl(g)+NH3(g)→GaN(s) A reaction of +HCl(g)+H2(g) takes place, and hydrogen chloride gas and hydrogen gas are supplied to the outlet. Further, in general, as a condition for growing a gallium nitride single crystal, ammonia gas (nitrogen source gas, group V source gas) may be excessively supplied as compared with gallium chloride gas (group III source gas). In such cases, unreacted ammonia gas is also contained in the exhaust gas. When the unreacted ammonia gas reacts with the hydrogen chloride gas produced as a by-product in the above reaction, solid ammonium chloride is produced. Since the sublimation point of ammonium chloride is 338° C. under normal pressure, the temperature of the collecting portion 340 is preferably 338° C. or lower in order to ensure that the solid ammonium chloride is collected by the collecting portion 340 . By doing so, the gas supplied to the exhaust gas treatment device 360 is only the unreacted ammonia gas in addition to the pushing gas. If both the ammonia gas and the hydrogen chloride gas pass through without being collected by the collection unit 340, solid ammonium chloride precipitates in the exhaust gas supply pipe 350, and there is a risk of clogging.

On the other hand, for example, when aluminum trichloride gas is used as the group III source gas and ammonia gas is used as the nitrogen source gas to grow an aluminum nitride single crystal, the ammonia gas supply flow rate is smaller than that for the gallium nitride single crystal. Conditions may be used. In this case, AlCl3(g)+NH3(g)→AlN(s)+3HCl(g) occurs in the growing part. In addition to the by-produced hydrogen chloride gas, unreacted aluminum chloride gas may be supplied to the discharge part. Since the sublimation point of aluminum chloride is 190° C., the temperature of the collecting portion is preferably 190° C. or lower, and more preferably 150° C. or lower for stable solidification. If the aluminum chloride passes through without being collected by the collecting portion 340, there is a risk of clogging due to precipitation of solid aluminum chloride in the exhaust gas supply pipe 350. FIG. Furthermore, if water or an aqueous solution is used as the collecting liquid for the exhaust gas treatment device 360, aluminum chloride reacts with water to generate high heat and white smoke of HCl, which is dangerous. By reliably collecting the aluminum chloride in the collecting section 340, the aluminum nitride single crystal can be grown safely and stably.

As described above, in addition to the case where the ammonia gas supply flow rate is small, even when the ammonia gas supply flow rate is large, when supplying a halogen-based gas in addition to the raw material gas as in Patent Document 1, the exhaust gas Thermodynamic analysis and elemental analysis by the present inventors revealed that aluminum chloride gas tends to remain. This is because the equilibrium of the reaction of AlCl3(g)+NH3(g)→AlN(s)+3HCl(g) shifts to the left due to the large amount of hydrogen chloride gas. This equilibrium shift is remarkable at 400° C. or less, and when hydrogen chloride gas is not supplied, aluminum chloride gas tends to react with ammonia gas to form aluminum nitride solids, but hydrogen chloride gas is supplied excessively. In this case, at 400° C. or below, no solid aluminum nitride is produced, and aluminum chloride gas remains in the gas component. Therefore, it is considered preferable to set the temperature of the collecting section 340 to 190° C. or lower, as in the case where the amount of ammonia gas supplied to the growth section reaction zone 201 is small. At this temperature, a reaction occurs in which unreacted ammonia gas and hydrogen chloride gas become solid ammonium chloride, and aluminum chloride and ammonium chloride are collected in the collecting section 340 . The gas supplied to the exhaust gas treatment device 360 is only hydrogen chloride gas in addition to the pushing gas.

When stainless steel is used for the pipes constituting the exhaust part 300, particularly the exhaust gas supply pipe 350, and water is used as the collection liquid for the exhaust gas treatment device 360, the gas supplied to the exhaust gas treatment device 360 is selected from the viewpoint of corrosion resistance. preferably does not contain acid gas. This is because if acidic gas is contained, the moisture in the exhaust gas treatment device 360 or moisture in the atmosphere that may come into contact with the acidic gas react with each other to form an acidic aqueous solution, which may corrode stainless steel. In order to stably collect the gas, it is preferable that the gas to be collected by the exhaust gas processing device 360 contained in the gas supplied to the exhaust gas processing device 360 has a high solubility in water. In the example described above, the case where the ammonia gas is supplied to the exhaust gas processing device 360 and the case where the hydrogen chloride gas is supplied to the exhaust gas processing device 360 are mentioned. Ammonia gas is more preferable as the gas to be supplied.

Therefore, when the amount of ammonia gas supplied to the growth reaction zone 201 is small, or when hydrogen chloride gas is supplied to the growth zone reaction zone 201, the hydrogen chloride gas is removed before it is supplied to the exhaust gas treatment device 360. It is desirable that the hydrogen chloride gas and a reactive gas that reacts with the hydrogen chloride gas are brought into contact with each other and collected by the collection unit 340 before being supplied to the exhaust gas treatment device 360 . For example, by supplying ammonia gas to the outlet reaction zone 320 and contacting it with hydrogen chloride gas, it can be collected by the collector 340 as ammonium chloride. In this case, the gas supplied to the exhaust gas treatment device 360 is unreacted ammonia gas.

In the discharge part reaction zone 320, depending on the temperature, solid ammonium chloride is generated, so it is preferable to provide a plurality of reactive gas supply ports 322 in as wide a region as possible (a position away from the wall surface). If a large amount of reactive gas is supplied from a narrow area or only from one supply port, ammonium chloride will concentrate and precipitate in that portion, which may cause clogging. Moreover, in order to reliably collect the hydrogen chloride gas as ammonium chloride in the collection section 340, it is preferable to increase the contact efficiency between the hydrogen chloride gas and the ammonia gas supplied to the discharge section reaction zone 320. For this reason as well, it is preferable that there are a plurality of reactive gas supply ports 322 , and that the discharge section reaction zone 320 is located upstream of the collection section 340 . The distance between the discharge part reaction zone 320 and the collection part 340, that is, the length of the exhaust gas supply pipe 330, may be any distance at which the hydrogen chloride gas and the ammonia gas are in complete contact and react. From the viewpoint of management, it is preferably 5 cm or more and 3 m or less, more preferably 10 cm or more and 2 m or less.

The reactive gas supplied to the outlet reaction zone 320 is preferably the same as the raw material gas for growing the group III nitride single crystal. Specifically, as in the above example, when a Group III nitride single crystal is grown using aluminum chloride gas and ammonia gas as raw material gases, the gas supplied to the exhaust reaction zone 320 is ammonia gas. is preferred.

Although the preferable state is shown when the pipe that constitutes the discharge part 300 is made of stainless steel and the collection liquid of the exhaust gas treatment device 360 is water, depending on the material of the pipe and the collection method in the exhaust gas treatment device 360, The gas supplied to the exhaust gas treatment device 360 can be an acidic gas, and for that reason, the gas supplied to the exhaust reaction zone 320 can also be an acidic gas.

<2. Method for producing group III nitride single crystal>
A method for producing a Group III nitride single crystal according to the second aspect of the present invention is characterized in that a Group III source gas and nitrogen are added to the growth section reaction zone of the Group III nitride single crystal production apparatus according to the first aspect of the present invention. It has a step of reacting the group III source gas and the nitrogen source gas by supplying the source gas (hereinafter sometimes simply referred to as step (a)). In step (a), a Group III nitride single crystal is grown on the substrate by the reaction between the Group III source gas and the nitrogen source gas.

In the following, as an apparatus for producing a group III nitride single crystal according to the first aspect of the present invention, an embodiment using the group III nitride single crystal production apparatus 100 described above will be described as an example.

The group III source gas supplied from the group III source gas supply nozzle 211 in the growth section 200 (FIG. 2) of the group III nitride single crystal manufacturing apparatus 100 includes aluminum halides such as aluminum chloride and aluminum bromide, gallium chloride, and the like. Group III halide gases such as gallium halides, indium halides such as indium chloride, etc., and group III organometallic compound gases such as trimethylaluminum and trimethylgallium can be employed without particular limitation. When producing mixed crystals, a mixed gas containing a plurality of group III source gases is used. When the HVPE method is employed, as described above, the group III metal raw material is placed in the raw material section reactor on the upstream side of the group III raw material gas supply nozzle 211, and the raw material section reactor is heated by an external heating device (for example, aluminum chloride gas When generating gallium chloride gas, it is usually about 150 to 1000 ° C., preferably about 300 to 660 ° C., more preferably about 300 to 600 ° C. When generating gallium chloride gas, it is usually about 300 to 1000 ° C. ), a group III halide gas generated in the raw material reactor by supplying a halogen-based gas (for example, hydrogen chloride gas, chlorine gas, etc.) to the raw material reactor is fed through the group III raw material gas supply nozzle 211. It can be introduced into the growth zone reaction zone 201 .

The present invention is suitable in the case where a halogen-based gas is also supplied when supplying the group III source gas and the nitrogen source gas to the growth zone reaction zone to produce the group III nitride. A halogen-based gas can be supplied from a halogen-based gas supply nozzle 212 . Further, the group III source gas may be supplied to the growth zone reaction zone 201 together with the group III source gas from the group III source gas outlet of the group III source gas supply nozzle 211 , or the nitrogen source may be supplied from the nitrogen source gas outlet of the nitrogen source gas supply nozzle 210 . It may be supplied to the growth zone reaction zone 201 together with the gas. Hydrogen chloride gas, chlorine gas, or the like can be used as the halogen-based gas, but it is preferably the same gas as the halogen-based gas supplied to the raw material section.

By joining the halogen-based gas with the group III halide gas generated in the raw material section, the gas composition ratio of the group III halide gas and the halogen-based gas can be controlled to an arbitrary composition ratio. However, when a gallium nitride gas is used as the group III raw material gas to produce a gallium nitride single crystal, the ratio of the simultaneous supply amounts of the group III added halogen-based gas and the halogenated gallium gas: (group III added Substance amount of halogen atoms in halogen-based gas)/(substance amount of halogen atoms in gallium halide gas) is preferably from 0.01 to 10, more preferably from 0.05 to 1. In the case of growing an aluminum nitride single crystal using an aluminum halide as the group III raw material gas, the ratio of the simultaneous supply amounts of the group III additional halogen-based gas and the aluminum halide gas: (group III additional halogen-based Substance amount of halogen atoms in gas)/(substance amount of halogen atoms in aluminum halide gas) is preferably 0.1-1000, more preferably 0.5-100. The calculation of the above ratio can also be performed based on the mass flow rate (mass of material passing through a given surface per unit time) generally used for controlling the gas supply rate in a crystal growth apparatus. Coexistence of the Group III additional halogen-based gas and the Group III raw material gas can suppress deposition of Group III metals due to disproportionation reaction of, for example, aluminum chloride gas or gallium chloride gas.

On the other hand, in place of the source material section in which the group III metal source material is placed, a separately generated group III source gas (group III halide gas in the case of the HVPE method, group III organometallic compound gas in the case of the MOCVD method, gas.) and heated to a desired temperature (for example, room temperature to 200° C.) by a heating device.

These Group III raw material gases and Group III additional halogen-based gases are usually supplied in a state diluted with a carrier gas. As the carrier gas, hydrogen gas, nitrogen gas, helium gas, argon gas, or a mixed gas thereof can be used without particular limitation, and a carrier gas containing hydrogen gas is preferably used. When supplying the group III source gas diluted with a carrier gas, the concentration of the group III source gas is based on the total amount of the group III source gas and the carrier gas that dilutes the group III source gas (100 volume %) can be, for example, 0.0001 to 10 volume %. The supply amount of the group III source gas can be, for example, 0.005 to 500 sccm. The Group III source gas is preferably supplied to the growth section reaction zone 201 (on the substrate 220 ) after starting the supply of the halogen-based gas onto the substrate 220 .

The nitrogen source gas supplied from the nitrogen source gas supply nozzle 210 to the growth zone reaction zone 201 is generally diluted with a carrier gas. As the nitrogen source gas, any reactive gas containing nitrogen can be used without particular limitation, but ammonia gas can be preferably used in terms of cost and ease of handling. As the carrier gas, hydrogen gas, nitrogen gas, helium gas, argon gas, or a mixed gas thereof can be used without particular limitation, and a carrier gas containing hydrogen gas is preferably used. When the nitrogen source gas is diluted with a carrier gas and supplied to the growth zone reaction zone 201, the supply amount of the nitrogen source gas and the supply amount of the carrier gas can be determined based on the size of the apparatus. can. Considering the ease of production of group III nitride single crystals, the supply amount of the carrier gas is preferably 50 to 10000 sccm, more preferably 100 to 5000 sccm. The concentration of the nitrogen source gas can be, for example, 0.0000001 to 10% by volume based on the total amount of the nitrogen source gas and the carrier gas that dilutes the nitrogen source gas (100% by volume). Also, the supply amount of the nitrogen source gas can be, for example, 0.01 to 1000 sccm. The order in which the nitrogen source gas is supplied onto the substrate 220 is not particularly limited. is preferably supplied to reaction zone 201 (on substrate 220).

The supply of the halogen-based gas to the growth part reaction zone 201 is preferably started before the group III source gas is supplied to the growth part reaction zone 201 . More specifically, it is preferable to start supplying the halogen-based gas onto the substrate 220 before the Group III source gas is supplied onto the substrate 220 . That is, it is preferable to start supplying the halogen-based gas onto the substrate 220 before the Group III source gas and the nitrogen source gas are supplied onto the substrate 220 and react with each other. The step (a) is repeated using the same group III nitride single crystal production apparatus 100 by starting to supply the halogen-based gas onto the substrate 220 before supplying the group III source gas onto the substrate 220. In a method for producing a group III nitride single crystal including the step (step (b)) of producing a plurality of group III nitride single crystals by performing can be reduced, and group III nitride single crystals of good quality can be produced stably.

When the halogen-based gas is started to be supplied onto the substrate 220 before the group III source gas is supplied onto the substrate 220, the halogen-based gas exits the nozzle outlet and is supplied onto the substrate 220. The time is defined by the supply flow rate of the halogen-based gas (or the supply flow rate of the halogen-based gas, for example, a carrier gas), and the volume in the reactor 202 from the outlet portion of the nozzle to which the halogen-based gas is supplied until it reaches the substrate 220. When supplied simultaneously with the gas, it can be obtained by dividing by the total supply flow rate of the other gas and the halogen-based gas (cm ³ /min). In addition, the time from the start of introduction of the halogen-based gas to the arrival of the halogen-based gas at the outlet of the nozzle is the length of the halogen-based gas from the inlet of the nozzle into which the halogen-based gas is introduced to the outlet The total volume in the piping that constitutes the movement path is the supply flow rate of the halogen-based gas (or, if the halogen-based gas and another gas such as a carrier gas are simultaneously distributed in the same piping, the other gas and the total supply flow rate of the halogen-based gas.). After the introduction of the halogen-based gas into the reactor 202 is started, the supply of the group III source gas is started after the time calculated by this method has elapsed, whereby the group III source gas is supplied onto the substrate 220. Halogen-based gas can be reliably supplied onto the substrate 220 before.

When the Group III source gas is obtained by reacting a metallic aluminum or organometallic gas with a halogen-based gas for source generation, the reaction between the metallic aluminum or organometallic gas and the halogen-based gas for source generation is intentionally left unreacted. It is also possible to generate a mixed gas of the III-group source gas and the halogen-based gas and supply the mixed gas to the growth part reaction zone 201 by controlling the reaction rate so that the gas remains.

Flow of group III halide gas (group III source gas) flowing out from group III source gas supply nozzle 211 and flow out from nitrogen source gas supply nozzle 210 in growth section reaction zone 201 of group III nitride single crystal manufacturing apparatus 100 A barrier gas flow may be interposed between the flow of the nitrogen source gas and the flow of the nitrogen source gas. As a barrier gas flowing out between the flow of the group III source gas and the flow of the nitrogen source gas, diffusion of the group III source gas and the nitrogen source gas into the barrier gas is slow because it is inert and has a large molecular weight. Nitrogen gas, argon gas, or a mixed gas thereof can be preferably used in terms of (high barrier effect). However, in order to adjust the effect of the barrier gas, nitrogen gas, argon gas, or a mixture of these gases should be combined with an inert gas such as hydrogen gas, helium gas, neon gas, etc. (that is, it does not react with the group III source gas and the nitrogen source gas). A low molecular weight gas may be mixed. The supply amount of the barrier gas is determined based on the size of the device, the effect of suppressing mixing, etc., and is not particularly limited, but can be, for example, 50 to 10,000 sccm, preferably, for example, 100 to 5000 sccm. be able to.

Examples of materials for the substrate 220 on which group III nitride single crystals are deposited include sapphire, silicon, silicon carbide, zinc oxide, gallium nitride, aluminum nitride, aluminum gallium nitride, gallium arsenide, zirconium boride, and titanium boride. Can be used without restrictions. Also, the thickness of the base substrate is not particularly limited, and can be, for example, 100 to 2000 μm. Further, the plane orientation of the crystal forming the substrate 12 is not particularly limited, and may be, for example, the +c plane, -c plane, m plane, a plane, r plane, or the like.

Thereafter, while introducing the nitrogen source gas into the growth section reaction zone 201 through the nitrogen source gas supply nozzle 210, the group III source gas is introduced into the growth section reaction zone 201 through the group III source gas supply nozzle 211, and the substrate 220 is heated. A III-nitride single crystal is grown thereon. At this time, as described above, after the halogen-based gas is supplied onto the substrate 220, the supply of the group III source gas is started, and the group III source gas and the nitrogen source gas are reacted to start crystal growth. is preferred.

The heating temperature of the substrate 220 during crystal growth may be appropriately determined according to the type of group III nitride single crystal for crystal growth, or the type of group III source gas and nitrogen source gas used as raw materials. For example, the temperature is 1000 to 1700° C., particularly preferably 1200 to 1650° C. when producing an aluminum nitride single crystal by HVPE, and preferably 1000 to 1600° C. when producing an aluminum nitride single crystal by MOCVD. be. When the HVPE method is used (that is, when a group III halide gas is used as the group III source gas), the growth of the group III nitride single crystal in the method for producing a group III nitride single crystal of the present invention is usually performed as follows. Under pressure near atmospheric pressure (that is, under conditions where the pressure inside the reactor, inside the group III raw material gas supply nozzle, and inside the nitrogen source gas supply nozzle is 0.1 to 1.5 atm. Manufacturing an aluminum nitride single crystal When using the MOCVD method (that is, when using a group III organometallic compound gas as the group III source gas), the pressure is usually 100 Pa or higher. It is carried out under atmospheric pressure.

When using the HVPE method, the supply amount of the group III raw material gas (group III halide gas) is the supply partial pressure (of the total supplied gas (carrier gas, group III raw material gas, nitrogen source gas, barrier gas, extrusion gas) The ratio of the volume of the group III source gas under standard conditions to the total volume under standard conditions.) is usually 1 Pa to 1000 Pa. When the MOCVD method is used, the supply amount of the group III source gas (group III organometallic compound gas) is usually 0.1 to 100 Pa in terms of supply partial pressure. The supply amount of the nitrogen source gas is not particularly limited, but is generally 0.5 to 1000 times, preferably 1 to 200 times, the Group III source gas to be supplied.

The growth time is appropriately adjusted so that the desired grown film thickness is achieved. After crystal growth is performed for a certain period of time, the crystal growth is terminated by stopping the supply of the Group III raw material gas. After that, the temperature of the substrate 220 is lowered to room temperature. Through the above operations, a Group III nitride single crystal can be grown on the substrate 220 .

The group III nitride single crystal manufacturing apparatus and the group III nitride single crystal manufacturing method of the present invention are not particularly limited, but a group III nitride single crystal, particularly nitriding, having a film thickness of 20 μm or more is formed on the substrate 220 . It can be preferably used when growing an aluminum single crystal, and can be particularly preferably used when growing a Group III nitride single crystal, especially an aluminum nitride single crystal, with a film thickness of 100 μm or more on the substrate 220 . Although the upper limit of the thickness of the group III nitride single crystal is not particularly limited, it can be, for example, 2000 μm or less. The size of the group III nitride single crystal, especially the aluminum nitride single crystal, is not particularly limited, but the area of the group III nitride single crystal grown on the substrate (the area of the crystal growth surface) is It is preferably 100 mm ² or more, more preferably 400 mm ² or more, and still more preferably 1000 mm ² or more. Although the upper limit of the area of the crystal growth surface is not particularly limited, it can be, for example, 10000 mm ² or less.

In the discharge section 300 (FIG. 5) of the group III nitride single crystal production apparatus 100, as described above, the temperature of the discharge gas supply pipe 311 is set to 50° C. or higher and 400° C. or lower in order to suppress solid precipitation. It is preferably 50° C. or higher and 300° C. or lower, more preferably.

In the outlet reaction zone 320 , a reactive gas that reacts with the gas discharged from the growth section 200 can be supplied in order to completely collect ammonium chloride and aluminum chloride in the collector 340 . The reactive gas to be supplied can be appropriately selected from hydrogen chloride gas, chlorine gas, ammonia gas, etc., depending on the material of the member constituting the discharge part and the group III nitride single crystal growth conditions, but the gas supplied to the growth part reaction zone 201 It preferably contains at least one gas selected from The supply flow rate of the reactive gas should be equal to or greater than the amount at which all of the gas components (hereinafter also referred to as “gas component A”) that react with the reactive gas in the gas discharged from the growth section 200 can completely react. preferable. The amount of gas component A in the gas discharged from the growth section 200 can be estimated from the growth rate of the group III nitride single crystal and the reaction rate of the parasitic reaction. is difficult, it is preferable to control as follows. For example, if the gas component A reacts with any gas supplied to the growth zone reaction zone other than the reactive gas supplied to the discharge zone reaction zone, it reacts with the gas component A supplied to the growth zone reaction zone 201. The total amount of the gas and the reactive gas supplied to the discharge section reaction zone 320 is the maximum amount of the gas component A in the gas supplied to the growth section and the gas component A by-produced in the growth section (reaction yield is 100% by-product) and the amount that reacts with the total amount without excess or deficiency. More preferably 1.1 times or more, still more preferably 1.2 times or more. By doing so, the contact efficiency between the gas component A and the reactive gas is increased, and the deposits caused by the gas component A can be collected in the collecting portion. The reactive gas can also be supplied together with a carrier gas such as nitrogen gas or hydrogen gas. When a plurality of reactive gas supply ports 322 are provided in the discharge section reaction zone 340, the total supply amount of the reactive gas is the sum of the gas component A in the gas supplied to the growth section and the gas component A by-produced in the growth section. The amount should be equal to or more than the sum of the maximum amount (the amount of by-products on the premise that the yield of the reaction is 100%) and the amount that reacts without excess or deficiency. For example, when aluminum chloride gas and ammonia gas are supplied to the growth part reaction zone 201 while supplying a halogen-based gas to grow aluminum nitride, ammonia gas is supplied to the discharge part reaction zone 320 and It can be collected as ammonium chloride by reacting with the by-produced hydrogen chloride. In this case, if the halogen-based gas supplied to the growth part reaction zone 201 is 100 sccm, the aluminum chloride gas is 10 sccm, and the ammonia gas is 40 sccm, the ammonia gas supplied to the discharge part reaction zone 320 is preferably 90 sccm or more, preferably 99 sccm. It is more preferably 108 sccm or more, and more preferably 108 sccm or more.

Further, as described above, before the group III source gas and the nitrogen source gas are reacted on the substrate 220 to grow the group III nitride, the growth part reaction zone 201 is supplied with a halogen-based gas, a group III source gas, and a nitrogen source gas. is preferably supplied to the exhaust reaction zone 320 even before growth. In this case, the reactive gas supplied before growth and the reactive gas supplied during growth are preferably the same gas.

As described above, the means for collecting in the collection unit 340 is not limited. Preferably, the collector 340 is cooled by external cooling means 342 . Specifically, the temperature is preferably 190° C. or lower, more preferably 150° C. or lower, and even more preferably 100° C. or lower.

<Treatment after manufacturing>
The resulting group III nitride single crystal is suitable for light emitting devices using aluminum-based group III nitride semiconductors (mainly aluminum gallium nitride mixed crystals), electronic devices such as Schottky barrier diodes and high electron mobility transistors, and the like. can be used for The group III nitride single crystal obtained by the production method of the present invention is ground to a desired thickness, if necessary, and then the surface is flattened by grinding, followed by chemical mechanical polishing (CMP). ) to remove the polishing damage layer caused by the grinding of the surface, thereby making it possible to obtain a Group III nitride single crystal with a flat surface. Alternatively, the base substrate may be removed by a known processing method such as mechanical cutting, laser cutting, or grinding to form a new group III nitride single crystal consisting of only the group III nitride single crystal layer laminated on the base substrate. can. Known methods can be employed for grinding and chemical mechanical polishing (CMP). Abrasives that can be used include materials such as silica, alumina, ceria, silicon carbide, boron nitride, and diamond. Moreover, the properties of the abrasive may be alkaline, neutral, or acidic. Among them, since aluminum nitride has low alkali resistance on the nitrogen polar plane (−c plane), weakly alkaline, neutral or acidic abrasives, specifically pH 9 or less abrasives, are preferred over strongly alkaline abrasives. is preferably used. Of course, if a protective film is provided on the nitrogen-polar surface, a strong alkaline abrasive can be used without any problem. Additives such as an oxidizing agent can be added to increase the polishing speed, and commercially available materials and hardness of the polishing pad can be used.

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

<Example 1>
(Growth of aluminum nitride single crystal layer)
(Preparation of base board)
A commercially available aluminum nitride single crystal substrate having a diameter of 22 mm and a thickness of 510 μm, which was produced by a sublimation method, was used as a base substrate. After ultrasonically cleaning the aluminum nitride single crystal substrate as the base substrate with acetone and isopropyl alcohol, the aluminum nitride single crystal substrate was subjected to BN deposition in an HVPE apparatus so that the Al polarity side of the aluminum nitride single crystal substrate became the growth surface. It was installed on a coated graphite susceptor.

(Conditions for manufacturing aluminum nitride single crystal)
For the growth of the aluminum nitride single crystal layer, in the HVPE apparatus (group III nitride single crystal production apparatus 100) of the mode shown in FIG. An apparatus provided with a rectifying partition was used. The rectifying partition is a quartz glass plate having 24 through-holes with a diameter of 3 mm and is welded to the inner wall of the quartz glass flow channel.

Through the through-holes of the rectifying partition, the carrier gas was circulated from the further upstream side of the flow channel. A mixed carrier gas of 6500 sccm in which hydrogen and nitrogen were mixed at a ratio of 7:3 was used as the extrusion carrier gas.

Further, 1500 sccm of nitrogen gas was supplied from a barrier gas nozzle. The pressure in the system during growth was kept at 0.9 atm.

6N grade high-purity aluminum was placed in the raw material section reactor further upstream from the group III raw material gas supply nozzle 211 . The inside of the raw material part reactor was heated to 400°C. The substrate 220 was heated to 1500°C.

(Structure of discharge part)
An exhaust reaction zone 320 with an internal volume of 5000 cm3 having a reactive gas supply pipe 321 having ten reactive gas supply ports 322 with a diameter of 10 mm in the center, and a diameter connected to the downstream end of the exhaust reaction zone 320. It has an exhaust gas supply pipe 330 with a length of 70 mm and a length of 1000 mm, and a collection part 340 connected to the other end of the exhaust gas supply pipe 330 . The collecting part 340 has an internal volume of 5000 cm 3 and has two commercially available filters 341 (Dynamesh PWC70-10SDOE manufactured by Pall Corporation) inside. The gas that has passed through the filter 341 is supplied to the exhaust gas treatment device 360 through an exhaust gas supply pipe 350 having a diameter of 23 mm. A dry pump was installed between the collection part 340 and the exhaust gas treatment device 360, and the pressure in the growth part reaction zone 201 was controlled to 0.9 atm. A pressure gauge was provided at an arbitrary position of the piping from the collection part 340 to the dry pump. Solid deposition occurs on the upstream side of the pressure gauge, and when the pipe diameter becomes narrow, pressure loss occurs, resulting in a differential pressure between the upstream side and the downstream side of the deposition point. In this example, the differential pressure was monitored, and it was determined that a sign of blockage had appeared when a differential pressure occurred. The exhaust gas supply pipe 311 was at a temperature of course, and the exhaust reaction zone 320 and the collector 340 were controlled at 50° C. by external cooling devices 323 and 342 . Seven liters of water was circulated through the exhaust gas treatment device 360 . Exhaust gas supply pipe 350 connected to exhaust gas treatment device 360 is made of stainless steel except for a part. The part is only 30 cm connected to the exhaust gas treatment device 360, and the part is made of vinyl chloride.

(Temperature of base substrate and growth of aluminum nitride single crystal)
When the raw material reactor reached 400° C. and the substrate 220 reached 1500° C., a total of 200 sccm of ammonia gas of 50 sccm and hydrogen carrier gas of 150 sccm was supplied from the nitrogen source gas supply nozzle 210 to the growth part reaction zone 201 . After 30 seconds, 10 sccm of aluminum chloride gas was generated by supplying 30 sccm of hydrogen chloride gas together with the carrier gas to the source reactor. A mixed gas of 1800 sccm in total including 1790 sccm of a hydrogen-nitrogen mixed carrier gas was introduced into the growth zone reaction zone 201 from the group III raw material supply nozzle outlet. In addition, 10 sccm of ammonia gas was supplied to the discharge part reaction zone 320 through the reactive gas supply pipe 321 at the same time as the hydrogen chloride gas was supplied to the raw material part reactor. Under the above conditions, an aluminum nitride single crystal layer was grown for 40 hours. After the growth of the aluminum nitride single crystal layer, the supply of aluminum chloride gas, hydrogen chloride gas and ammonia gas was stopped and the substrate 220 was cooled to room temperature.

(Analysis of Exhaust Blockage State and Exhaust Gas from Exhaust Gas Processing Equipment)
No differential pressure occurred during 40 hours of aluminum nitride single crystal growth. Further, when the exhaust gas supply pipe 350 was opened to the atmosphere after the growth, no precipitate was found. After 40 hours from the start of the growth, just before the end of the growth, a pH test paper moistened with ultrapure water was brought close to the exhaust port 361 of the exhaust gas treatment device 360, and a pH of 7 was indicated.

<Example 2>
In the supply of the group III raw material gas and the halogen-based gas, as shown in FIG. 3, 100 sccm of hydrogen chloride gas was supplied to the generated aluminum chloride gas from the group III additional halogen-based gas supply nozzle, and 1690 sccm of the hydrogen-nitrogen mixed carrier gas was supplied. 1800 sccm in total including An aluminum nitride single crystal was grown by the same growth method.

No differential pressure occurred during 40 hours of aluminum nitride single crystal growth. Further, when the exhaust gas supply pipe 350 was opened to the atmosphere after the growth, no precipitate was found. After 40 hours from the start of the growth, just before the end of the growth, a pH test paper moistened with ultrapure water was brought close to the exhaust port 361 of the exhaust gas treatment device 360, and a pH of 7 was indicated.

<Comparative Example 3>
The exhaust reaction zone 320 and the exhaust gas supply pipe 330 used in Example 2 are removed, and one reactive gas supply port 322 is provided from the upstream side of the outer wall of the collection part 340, and the collection part 340 and the discharge reaction zone An aluminum nitride single crystal was grown by the same growth method as in Example 2, except that the structure also served as 320.

No differential pressure occurred during 40 hours of aluminum nitride single crystal growth. Further, when the exhaust gas supply pipe 350 was opened to the atmosphere after the growth, a slight amount of precipitate of ammonium chloride was found inside the pipe 350 . After 40 hours from the start of the growth, just before the end of the growth, a pH test paper moistened with ultrapure water was brought close to the exhaust port 361 of the exhaust gas treatment device 360, and a pH of 7 was indicated.

<Comparative Example 4>
An aluminum nitride single crystal was grown by the same growth method as in Comparative Example 3 , except that the temperature of the collecting portion 340 was set to 200.degree.

No differential pressure occurred during 40 hours of aluminum nitride single crystal growth. Further, when the exhaust gas supply pipe 350 was opened to the atmosphere after the growth, a slight deposit of aluminum chloride and ammonium chloride was found. When pH test paper moistened with ultrapure water was brought close to the exhaust port 361 of the exhaust gas treatment device 360 just before the growth chief after 40 hours from the start of growth, a pH of 7 was indicated.

<Comparative Example 1>
An aluminum nitride single crystal was grown by the same growth method as in Example 1, except that the discharge section reaction zone 320, the collection section 340, and the exhaust gas supply pipe 330 were not provided, and the reactive gas was not supplied. .

After 13 hours of growth, a differential pressure developed and stopped growth. Further, when the exhaust gas supply pipe 350 was opened to the atmosphere after the growth, deposits of aluminum chloride and ammonium chloride were found. Thirteen hours after the start of the growth, just before the end of the growth, a pH test paper moistened with ultrapure water was brought close to the exhaust port 361 of the exhaust gas treatment device 360, and a pH of 7 was indicated.

<Comparative Example 2>
An aluminum nitride single crystal was grown by the same growth method as in Example 2 except that the exhaust reaction zone 320, the trapping part 340 and the exhaust gas supply pipe 330 were not provided and the reactive gas was not supplied. .

A differential pressure occurred after the growth for 6 hours, and when the exhaust gas supply pipe 350 was opened to the atmosphere after the growth, deposits of aluminum chloride and ammonium chloride were found. 40 hours after the start of the growth, just before the end of the growth, a pH test paper moistened with ultrapure water was brought close to the exhaust port 361 of the exhaust gas treatment device 360, and the pH was 6.5.

100. Vapor deposition equipment (HVPE equipment)
200. growing part 201 . Growth zone reaction zone
202. reaction tube
203. Substrate holding table 204 . heating means 205 . external heating means 210 . Nitrogen source gas supply nozzle 211 . Group III raw material gas supply nozzle 212 . Halogen gas supply nozzle 220 . Substrate 300 . discharge section 311 . Exhaust gas supply pipe 312 . external heating or cooling means 320 . Exhaust reaction zone 321 . reactive gas supply pipe 322 . Reactive gas supply port 330 . Exhaust gas supply pipe 331 . external heating or cooling means 340 . Collection unit 341 . filter 342 . external cooling means 350 . Exhaust gas supply pipe 360 . Exhaust gas treatment device 361 . exhaust port

Claims (4)

A growth section having a growth section reaction zone for growing a group III nitride single crystal on a substrate by reacting a group III source gas and a nitrogen source gas, and a discharge section for discharging gas that has passed through the growth section. A vapor phase growth apparatus,
The discharge unit includes a collection unit that collects at least one component of the exhaust gas that has passed through the growth unit, and an exhaust gas treatment device that collects at least one component in the exhaust gas that has passed through the collection unit,
The group III source gas is an aluminum halide gas, the nitrogen source gas is ammonia gas, the group III nitride single crystal is an aluminum nitride single crystal,
The exhaust gas contains aluminum chloride gas and hydrogen chloride gas,
Between the growth section and the collection section,
an exhaust gas reaction zone for supplying ammonia gas that reacts with the hydrogen chloride gas out of the exhaust gas that has passed through the growth section, and causing the hydrogen chloride gas component in the exhaust gas that has passed through the growth section to react with the ammonia gas; has
The exhaust gas reaction zone is connected to the growth section by a first exhaust gas supply pipe and is connected to the trapping section by a second exhaust gas supply pipe . having a plurality of gas supply ports,
The second exhaust gas supply pipe has a length of 10 cm or more and 2 m or less,
The collecting unit is equipped with a filter and an external cooling device to collect aluminum chloride and ammonium chloride ,
The exhaust gas treatment device includes a collection liquid containing water,
A vapor phase growth apparatus, wherein the temperature of the collecting part is 190° C. or lower. The exhaust gas reaction zone is an ammonia gas supply having a plurality of the ammonia gas supply ports. with a tube,
The vapor phase growth apparatus according to claim 1. a reaction tube in which the growth section has a growth section reaction zone for growing a group III nitride single crystal on a substrate by reacting the group III source gas and the nitrogen source gas;
a holding table disposed in the reaction zone of the growth section and holding a substrate;
a group III source gas supply nozzle for supplying a group III source gas to the reaction zone;
a nitrogen source gas supply nozzle for supplying the nitrogen source gas to the growth zone reaction zone;
3. The vapor phase growth apparatus according to claim 1, further comprising a structure for supplying at least one halogen-based gas selected from hydrogen halide gas and halogen gas to the reaction zone of the growth section. By supplying an aluminum halide gas as a group III source gas and an ammonia gas as a nitrogen source gas to the growth zone reaction zone of the vapor phase growth apparatus according to any one of claims 1 to 3 , a step of reacting the group III source gas and the nitrogen source gas,
A method for producing an aluminum nitride single crystal, which is a Group III nitride single crystal, wherein in the step, at least one halogen-based gas selected from hydrogen halide gas and halogen gas is supplied to the reaction zone of the growth part.

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