Manufacturing apparatus and manufacturing method of group iii nitride crystal

Abstract

To provide a manufacturing apparatus of a group III nitride crystal capable of manufacturing a high-quality group III nitride crystal by suppressing parasitic growth.SOLUTION: A manufacturing apparatus of a group III nitride crystal includes a raw material chamber for generating group III element oxide gas, and a rearing chamber for generating a group III nitride crystal on a seed substrate by reacting group III element oxide gas supplied from the raw material chamber with nitrogen element containing gas. The rearing chamber has a decomposition acceleration part for accelerating decomposition of unreacted nitrogen element containing gas, between an exhaust port for exhausting unreacted group III oxide gas and nitrogen element containing gas and the seed substrate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a manufacturing apparatus and method for Group III nitride crystals. [Background technology]

[0002] Group III nitride crystals such as GaN are expected to be applied to next-generation optical devices such as high-power LEDs (light-emitting diodes) and LDs (laser diodes), as well as next-generation electronic devices such as high-power power transistors to be mounted on EVs (electric vehicles) and PHVs (plug-in hybrid vehicles), etc. As a method for producing Group III nitride crystals, Oxide Vapor Phase Epitaxy (OVPE) using Group III oxides as raw materials is used (see, for example, Patent Document 1).

[0003] An example of the reaction system in the OVPE method is as follows: Ga is heated, and in this state, HO gas is introduced. The introduced HO gas reacts with Ga to generate GaO gas (represented by formula (I) below). Then, NH gas is introduced, and the NH gas reacts with the generated GaO gas to generate GaN crystals on the seed substrate (represented by formula (II) below). 2Ga(l)+H2O(g)→Ga2O(g)+H2(g)...(I) Ga2O(g)+2NH3(g)→2GaN(s)+H2O(g)+2H2(g)...(II) [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2015 / 053341 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the manufacturing method described in Patent Document 1, when growing a Group III nitride crystal, unreacted Group III oxide gas reacts with a nitrogen-containing gas downstream of the Group III nitride crystal, potentially resulting in parasitic growth of the Group III nitride crystal on the reactor wall or exhaust piping. The parasitic growth of the Group III nitride crystal (hereinafter referred to as "parasitic crystal") has a thermal expansion coefficient different from that of the material of the reactor wall. The difference in thermal expansion coefficient between the reactor wall and the parasitic crystal may cause damage or deterioration, such as cracking or chipping, of the reactor during the temperature increase / decrease process in the production of the Group III nitride crystal. Furthermore, the parasitic crystal generated on the reactor wall serves as a particle source in the growth space of the Group III nitride crystal. Therefore, particles from the parasitic crystal may scatter onto the Group III nitride crystal grown on the seed substrate, potentially causing abnormal growth, such as polycrystallization or the occurrence of pits in the grown crystal. Furthermore, if parasitic growth occurs in the exhaust piping, it may block the exhaust piping, hindering long-term growth.

[0006] The present disclosure is intended to solve the above problems, and has an object to provide a Group III nitride crystal manufacturing apparatus and manufacturing method that can suppress parasitic growth and produce high-quality Group III nitride crystals. [Means for solving the problem]

[0007] A Group III nitride crystal manufacturing apparatus according to the present disclosure includes a source chamber for generating a Group III element oxide gas, and a growth chamber for growing a Group III nitride crystal on a seed substrate by reacting the Group III oxide gas supplied from the source chamber with a nitrogen-containing gas. The growth chamber has a decomposition promoting section for promoting decomposition of the unreacted nitrogen-containing gas between the seed substrate and an exhaust port for exhausting the unreacted Group III oxide gas and the nitrogen-containing gas.

[0008] The method for producing a Group III nitride crystal of the present disclosure includes reacting a Group III element source with a reactive gas to produce a Group III element oxide gas, reacting the Group III element oxide gas with a nitrogen-containing gas to produce a Group III nitride crystal on a seed substrate, and decomposing a portion of the unreacted nitrogen-containing gas between the seed substrate and an exhaust port through which the unreacted Group III oxide gas and nitrogen-containing gas are exhausted. [Effects of the Invention]

[0009] According to the Group III nitride crystal manufacturing apparatus and manufacturing method according to the present disclosure, parasitic growth can be suppressed, and high-quality Group III nitride crystal can be manufactured. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view showing the configuration of a group III nitride crystal manufacturing apparatus according to an embodiment of the present disclosure. [Figure 2] 1 is a flowchart showing a method for manufacturing a group III nitride crystal according to an embodiment of the present disclosure. [Figure 3] 1 is a graph showing the relationship between the normalized surface area of ​​the decomposition promoting portion normalized by the cross-sectional area of ​​the growth chamber and the decomposition rate of NH 3 gas. DETAILED DESCRIPTION OF THE INVENTION

[0011] A Group III nitride crystal manufacturing apparatus according to a first aspect comprises a source chamber for generating a Group III element oxide gas, and a growth chamber for reacting a Group III element oxide gas supplied from the source chamber with a nitrogen-containing gas to grow a Group III nitride crystal on a seed substrate, the growth chamber having a decomposition promoting section for promoting decomposition of the unreacted nitrogen-containing gas between the seed substrate and an exhaust port for exhausting the unreacted Group III element oxide gas and nitrogen-containing gas.

[0012] The manufacturing apparatus for group III nitride crystals according to the second aspect may include at least one element selected from the group consisting of Mo, Ni, Fe, Co, Ti, Cr, Zr, Ta, W, and Pt in the first aspect.

[0013] The manufacturing apparatus for group III nitride crystals according to the third aspect may have a total surface area of the decomposition promoting portion that is 5 times or more the cross-sectional area of the growth chamber in the first or second aspect.

[0014] The manufacturing method for group III nitride crystals according to the fourth aspect includes reacting a group III element source and a reactive gas to generate a group III element oxide gas, reacting the group III element oxide gas and a nitrogen element-containing gas to form a group III nitride crystal on a seed substrate, and decomposing a part of the unreacted nitrogen element-containing gas between the seed substrate and the exhaust port.

[0015] Hereinafter, a manufacturing apparatus for group III nitride crystals and a manufacturing method for group III nitride crystals according to embodiments will be described with reference to the accompanying drawings. In the drawings, substantially the same members are denoted by the same reference numerals.

[0016] (Embodiment 1)

[0017] <Outline of the Manufacturing Apparatus for Group III Nitride Crystals> The outline of the manufacturing apparatus for group III nitride crystals according to Embodiment 1 of the present disclosure will be described with reference to the schematic cross-sectional view of FIG. 1. Note that FIG. 1 is a schematic diagram, and the sizes, ratios, etc. of each component may be different from the actual ones. The III nitride crystal manufacturing apparatus according to the first embodiment has a raw material chamber 100. A raw material reaction chamber 101 is arranged within the raw material chamber 100, and a raw material boat 104 having a starting group III element source 105 placed therein is arranged within the raw material reaction chamber 101. In the first embodiment, the starting group III element source 105 is a starting Ga source. A reactive gas supply pipe 103 is connected to the raw material reaction chamber 101, which supplies a reactive gas that reacts with the starting group III element source 105. The raw material reaction chamber 101 has a group III element oxide gas outlet 107. When the starting group III element source 105 is an oxide, a reducing gas is used as the reactive gas. When the starting group III element source 105 is a metal, an oxidizing gas is used as the reactive gas. The raw material chamber 100 is also provided with a first carrier gas supply port 102. The first carrier gas supplied from the first carrier gas supply port 102 carries the Group III element oxide gas discharged from the Group III element oxide gas discharge port 107 through the gas discharge port 108 and the connecting pipe 109 to the growth chamber 111. The growth chamber 111 has a gas supply port 118 for supplying the Group III element oxide gas and the first carrier gas, a third carrier gas supply port 112, a nitrogen-containing gas supply port 113, a second carrier gas supply port 114, an exhaust port 119, and a decomposition promoting section 120. A substrate susceptor 117 on which a seed substrate 116 is placed is disposed within the growth chamber 111.

[0018] In the manufacturing apparatus for group-III nitride crystals of the present disclosure, a decomposition promotion section is installed downstream of the substrate susceptor 117 in the growth chamber. As a result, even when unreacted group-III element oxide gas and nitrogen element-containing gas flow downstream of the substrate susceptor 117 during the crystal growth process, the nitrogen element-containing gas can be decomposed by the decomposition promotion section. Even when there is no decomposition promotion section, the nitrogen element-containing gas may be decomposed to some extent by heat, but it cannot be decomposed sufficiently to prevent parasitic growth. By arranging the decomposition promotion section, the decomposition of the nitrogen element-containing gas can be further promoted. Therefore, parasitic growth of group-III nitride crystals on the reactor wall and exhaust pipe in the growth chamber can be suppressed. As a result, breakage of the reactor and exhaust pipe can be prevented, and reliable production of group-III nitride crystals can be carried out. In addition, since breakage in the growth chamber can be reduced, maintenance costs can be suppressed, and the manufacturing cost of group-III nitride crystals can be reduced. Further, by preventing parasitic growth, it is possible to prevent the parasitic group-III nitride crystals (parasitic crystals) from becoming a particle source and scattering onto the group-III nitride crystals grown on the seed substrate. For this reason, abnormal growth such as polycrystallization and pit generation can be suppressed, and the quality of group-III nitride crystals can be improved.

[0019] <Outline of the method for manufacturing group-III nitride crystals> The outline of the method for manufacturing group-III nitride crystals according to an embodiment of the present disclosure will be described with reference to the flowchart of FIG. 2. In the present embodiment, the method for manufacturing group-III nitride crystals includes a reactive gas supply step, a group-III element oxide gas generation step, a group-III element oxide gas supply step, a nitrogen element-containing gas supply step, a group-III nitride crystal generation step, a residual nitrogen element-containing gas decomposition step, and a residual gas discharge step.

[0020] <Reactive gas supply step> In the reactive gas supply step, the reactive gas is supplied from the reactive gas supply pipe 103 to the raw material reaction chamber 101 in the raw material chamber 100. As described above, the reactive gas can use a reducing gas or an oxidizing gas as necessary. <Group III Oxide Gas Generation Step> In the Group III oxide gas generation step, in the raw material reaction chamber 101, a starting Group III element source 105 is reacted with a reactive gas (a reducing gas when the starting Group III element source is an oxide, and an oxidizing gas when the starting Group III element source is a metal) to generate a Group III oxide gas.

[0021] <Group III Oxide Gas Supply Step> In the Group III oxide gas supply step, the Group III oxide gas produced in the Group III oxide gas generation step is supplied to the growth chamber 111. The Group III oxide gas is discharged from the inside of the raw material reaction chamber 101 through the Group III oxide gas discharge port 107, discharged from the gas discharge port 108 together with the first carrier gas supplied from the first carrier gas supply port 102, conveyed through the connecting pipe 109, and supplied into the growth chamber 111 from the gas supply port 118.

[0022] <Nitrogen Element-Containing Gas Supply Step> In the nitrogen element-containing gas supply step, a nitrogen element-containing gas is supplied from the nitrogen element-containing gas supply port 113 to the growth chamber 111.

[0023] <Group III Nitride Crystal Growth Step> In the Group III nitride crystal growth step, the Group III oxide gas supplied into the growth chamber 111 in the Group III oxide gas supply step is reacted with the nitrogen element-containing gas supplied into the growth chamber 111 in the nitrogen element-containing gas supply step to grow a Group III nitride crystal on the seed substrate 116.

[0024] <Residual Nitrogen Element-Containing Gas Decomposition Step> In the residual nitrogen element-containing gas decomposition step, the unreacted nitrogen element-containing gas is decomposed by the decomposition promotion unit 120. Thereby, the parasitic growth of the Group III nitride crystal is suppressed. In the flowchart, the arrows indicate the sequence between processes. In reality, however, each process shown in the flowchart may be performed simultaneously. The flowchart shows the processes in the III-nitride crystal manufacturing apparatus from the upstream processes to the downstream processes with arrows.

[0025] <Residual gas discharge process> In the residual gas discharge process, the residual gas containing unreacted group-III oxide gas and nitrogen element-containing gas that does not contribute to the formation of III-nitride crystals is discharged from the exhaust port 119 to the outside of the growth chamber 111.

[0026] <Details of the method and apparatus for manufacturing III-nitride crystals> The details of the method for manufacturing III-nitride crystals according to this embodiment will be described. In this embodiment 1, metallic Ga is used as the starting group-III element source 105. <Reactive gas supply process> In the reactive gas supply process, the reactive gas is supplied from the reactive gas supply pipe 103 to the raw material reaction chamber 101. In this embodiment 1, since metallic Ga is used as the starting group-III element source 105, H2O gas is used as the reactive gas. Note that as the reactive gas, O2 gas, CO gas, NO gas, N2O gas, NO2 gas, or N2O4 gas may be used.

[0027] <Group-III element oxide gas generation process> In the group-III element oxide gas generation process, the reactive gas supplied to the raw material reaction chamber 101 in the reactive gas supply process reacts with Ga, which is the starting group-III element source 105, to generate Ga2O gas, which is a group-III element oxide gas. The generated Ga2O gas is discharged from the raw material reaction chamber 101 to the raw material chamber 100 via the group-III element oxide gas discharge port 107. The discharged Ga2O gas is mixed with the first carrier gas supplied from the first carrier gas supply port 102 to the raw material chamber 100 and is supplied to the gas discharge port 108. In the first embodiment, the raw material chamber 100 is heated by the first heater 106. When heating the raw material chamber 100, it is preferable that the temperature of the raw material chamber 100 be 800°C or higher, which is higher than the boiling point of the Ga2O gas. Also, it is preferable that the temperature of the raw material chamber 100 be lower than that of the growth chamber 111. As will be described later, when heating the growth chamber 111 by the second heater 115, it is preferable that the temperature of the raw material chamber 100 be, for example, less than 1800°C. The starting group III element source 105 is placed in the raw material boat 104 arranged in the raw material reaction chamber 101. The raw material boat 104 preferably has a shape that can increase the contact area between the reactive gas and the starting group III element source 105. For example, in order to prevent the starting group III element source 105 and the reactive gas from passing through the raw material reaction chamber 101 in a non-contact state, the raw material boat 104 preferably has a multi-stage dish shape.

[0028] Note that the methods for generating the group III element oxide gas are roughly classified into a method of reducing the starting group III element source 105 and a method of oxidizing the starting group III element source 105. For example, in the reduction method, an oxide (e.g., Ga2O3) is used as the starting group III element source 105, and a reducing gas (e.g., H2 gas, CO gas, CH4 gas, C2H6 gas, H2S gas, SO2 gas) is used as the reactive gas. On the other hand, in the method of oxidizing the starting group III element source 105, a non-oxide (e.g., liquid Ga) is used as the starting group III element source 105, and an oxidizing gas (e.g., H2O gas, O2 gas, CO gas, NO gas, N2O gas, NO2 gas, N2O4 gas) is used as the reactive gas. In addition to the Ga source, an In source and an Al source may be used as the starting group III element source 105. As the first carrier gas, an inert gas, H2 gas, etc. can be used.

[0029] <Group III Element Oxide Gas Supply Step> In the group III element oxide gas supply step, the Ga2O gas generated in the group III element oxide gas generation step is supplied to the growth chamber 111 via the gas outlet 108, the connecting pipe 109, and the gas supply port 118. If the temperature of the connecting pipe 109 connecting the raw material chamber 100 and the growth chamber 111 drops below the temperature of the raw material chamber 100, a reverse reaction of the reaction to generate the group III element oxide gas may occur, and there is a risk that the starting group III element source 105 will precipitate in the connecting pipe 109. Therefore, it is preferable that the connecting pipe 109 is heated by the third heater 110 so as not to drop below the temperature of the raw material chamber 100.

[0030] <Nitrogen element-containing gas supply step> In the nitrogen element-containing gas supply step, the nitrogen element-containing gas is supplied from the nitrogen element-containing gas supply port 113 to the growth chamber 111. Examples of the nitrogen element-containing gas include NH3 gas, NO gas, NO2 gas, N2O gas, N2O4 gas, N2H2 gas, and N2H4 gas. In the group III nitride crystal growth step, through each supply step, the raw material gas supplied into the growth chamber 111 is reacted to grow group III nitride crystals on the seed substrate 116. The growth chamber 111 is preferably heated by the second heater 115 to a high temperature up to the temperature at which the group III element oxide gas and the nitrogen element-containing gas react. At this time, in order to prevent the reverse reaction of the reaction to generate the group III element oxide gas from occurring, it is preferable to control the temperature of the growth chamber 111 so that the temperature of the growth chamber 111 does not drop below the temperature of the raw material chamber 100 and the temperature of the connecting pipe 109. The temperature of the growth chamber 111 heated by the second heater 115 is preferably 1000 °C or higher and 1800 °C or lower.

[0031] <Group III nitride crystal growth step> By mixing the group III element oxide gas supplied to the growth chamber 111 through the group III element oxide supply step and the nitrogen element-containing gas supplied to the growth chamber 111 through the nitrogen element-containing gas supply step upstream of the seed substrate 116, the growth of group III nitride crystals can be performed on the seed substrate 116.

[0032] <Residual nitrogen element-containing gas decomposition process> In the residual nitrogen-containing gas decomposition step, the nitrogen-containing gas that was not consumed in the Group III nitride crystal growth step is inactivated by the decomposition promoter 120. The decomposition promoter 120 is disposed downstream of the seed substrate 116, i.e., downstream of the substrate susceptor 117 that holds the seed substrate 116, so as not to impede the growth of the Group III nitride crystal on the seed substrate 116. In other words, the decomposition promoter 120 is disposed between the substrate susceptor 117 and the exhaust port 119. By decomposing and inactivating the nitrogen-containing gas in the decomposition promoter 120, it is possible to suppress the reaction between the nitrogen-containing gas that was not used in the growth of the Group III nitride crystal and the Group III oxide gas downstream of the seed substrate 116, and to prevent parasitic growth of the Group III nitride crystal on the reactor walls and exhaust piping. Reducing the parasitic growth of the Group III nitride crystal on the reactor walls and exhaust piping enables highly reliable production and reduces maintenance costs. Furthermore, the crystal quality is improved by reducing particles caused by parasitic growth. For example, when the group III nitride crystal is gallium nitride and NH3 gas is used as the nitrogen-containing gas, the decomposition reaction of the nitrogen-containing gas is expressed by the following formula (III). 2NH3(g)→N2(g)+3H2(g)...(III)

[0033] The material of the decomposition accelerating portion 120 preferably contains an active metal from the viewpoint of the catalytic effect of the decomposition reaction of the nitrogen-containing gas. Furthermore, since the growth chamber 111 is a high-temperature environment of approximately 1200°C, it is necessary that the material constituting the decomposition accelerating portion 120 does not melt at this temperature. Specifically, the decomposition accelerating portion 120 preferably contains at least one element selected from the group consisting of Mo, Ni, Fe, Co, Ti, Cr, Zr, Ta, W, and Pt. In particular, Mo, Ta, W, Zr, Cr, and Pt have melting points of 1700°C or higher. Therefore, even when the growth chamber 111 is heated using the second heater 115, they are less likely to deteriorate due to softening or to form an alloy with Ga, and are less likely to react with the reactive gas. Therefore, it is more preferable that the decomposition accelerating portion 120 contains at least one element selected from Mo, Ta, Zr, Cr, and Pt.

[0034] From the viewpoint of promoting the decomposition of the nitrogen-containing gas, it is preferable that the decomposition promotion section 120 has a larger surface area to improve the surface contact rate with the nitrogen-containing gas. The surface area of ​​the decomposition promotion section 120 refers to the total area of ​​the front and back surfaces of a single metal plate, for example. From the viewpoint of improving the decomposition rate, the total surface area of ​​the decomposition promotion section 120 is preferably a normalized surface area of ​​5 or more, more preferably 16.5 or more, and particularly preferably 32 or more, when the reactor cross-sectional area of ​​the growth chamber 111 is normalized to 1. To increase the surface area of ​​the decomposition promotion section 120, a punched plate-shaped multilayer body or porous body may be used. The multilayer body may be, for example, a plurality of metal plates arranged with spacers between them. Sponge-like metals, such as sponge-like iron, may also be used. Furthermore, a honeycomb-structured metal or ceramic support having fine particles of Pt or the like supported on the inner surface may also be used. This allows the nitrogen-containing gas to be decomposed downstream of the substrate susceptor 117, making it possible to more efficiently suppress the parasitic growth of group III nitride crystals.

[0035] The decomposition promoting portion 120 may have any shape as long as it does not hinder the discharge of gas from the exhaust port 119. The decomposition promoting portion 120 may be, for example, in the shape of a plate or an annular ring. The decomposition promoting section 120 is preferably installed in a region downstream of the substrate susceptor where the temperature is 800° C. or higher, from the viewpoint of promoting the decomposition of the nitrogen element-containing gas.

[0036] Alternatively, the concentrations of the Group III element oxide gas and the nitrogen-containing gas may be controlled by supplying a second carrier gas from the second carrier gas supply port 114 to the growth chamber 111. In this case, parasitic growth of Group III nitride crystals on the furnace wall of the growth chamber 111 and the substrate susceptor 117 can be suppressed.

[0037] Examples of seed substrates 116 include gallium nitride, gallium arsenide, silicon, sapphire, silicon carbide, zinc oxide, gallium oxide, and ScAlMgO4.

[0038] The second carrier gas may be an inert gas, H2 gas, or the like.

[0039] The unreacted Group III element oxide gas and nitrogen element-containing gas, as well as residual gases such as the first carrier gas, second carrier gas, and third carrier gas, are exhausted from the exhaust port 119 . [Example]

[0040] (Summary of Examples and Comparative Examples) Group III nitride crystals were grown using a growth furnace, a Group III nitride crystal manufacturing equipment shown in Figure 1. Here, GaN was grown as the Group III nitride crystal. Liquid Ga was used as the starting Ga source, and Ga was reacted with H2O gas, a reactive gas, and the resulting Ga2O gas was used as the Group III element oxide gas. NH3 gas was used as the nitrogen-containing gas, and a mixture of H2 gas and N2 gas was used as the first and second carrier gases. A freestanding GaN substrate was used as the seed substrate. The growth time was 1 hour for verification. The decomposition rate of NH3 was measured using gas chromatography.

[0041] Example 1 The growth conditions were a growth chamber temperature of 1200°C and a source chamber temperature of 1100°C. The partial pressures of GaO gas, H2O gas, NH3 gas, H2 gas, and N2 gas were 0.00108 atm, 0.00045 atm, 0.15748 atm, 0.71850 atm, and 0.12249 atm, respectively. Crystal growth was performed for one hour. A circular porous Ni decomposition promoter with a surface area 25.527 times the cross-sectional area of ​​the reactor (normalized surface area: 25.527) was installed downstream of the substrate susceptor, i.e., between the substrate susceptor and the exhaust port. As a result of growing GaN, the growth rate of GaN grown on the seed substrate was 94 μm / h, and the NH3 decomposition rate was 99.5%. No parasitic growth of GaN was observed on the reactor wall downstream of the substrate susceptor or on the exhaust piping. The NH3 decomposition rate was calculated from the NH3 gas concentration in the total gas flowing into the growth chamber and the NH3 gas concentration at the exhaust port.

[0042] Example 2 The growth conditions were a growth chamber temperature of 1200°C and a source chamber temperature of 1100°C. The partial pressures of GaO gas, H2O gas, NH3 gas, H2 gas, and N2 gas were set at 0.00106 atm, 0.00048 atm, 0.15749 atm, 0.71849 atm, and 0.12249 atm, respectively, and crystal growth was performed for one hour. A circular porous Ni decomposition promoter with a surface area 31.909 times the cross-sectional area of ​​the reactor (normalized surface area 31.909) was installed downstream of the substrate susceptor, i.e., between the substrate susceptor and the exhaust port. As a result of GaN growth, the growth rate was 116 μm / h and the NH3 decomposition rate was 100%. No parasitic growth of GaN was observed on the reactor wall downstream of the substrate susceptor or on the exhaust piping.

[0043] Example 3 The growth conditions were a growth chamber temperature of 1200°C and a source chamber temperature of 1100°C. The partial pressures of GaO gas, H2O gas, NH3 gas, H2 gas, and N2 gas were 0.00109 atm, 0.00044 atm, 0.15748 atm, 0.71850 atm, and 0.12249 atm, respectively. Crystal growth was performed for one hour. A circular porous Ni decomposition promoter with a surface area 63.818 times the cross-sectional area of ​​the reactor (normalized surface area: 63.818) was installed downstream of the substrate susceptor, i.e., between the substrate susceptor and the exhaust port. As a result of GaN growth, the growth rate was 111 μm / h and the NH3 decomposition rate was 100%. No parasitic growth of GaN was observed on the reactor wall downstream of the substrate susceptor or on the exhaust piping.

[0044] Example 4 The growth conditions were a growth chamber temperature of 1200°C and a source chamber temperature of 1100°C. The partial pressures of GaO gas, HO gas, NH gas, H gas, and N gas were 0.00107 atm, 0.00046 atm, 0.15748 atm, 0.71850 atm, and 0.12249 atm, respectively, and crystal growth was carried out for one hour. A circular multilayer Mo punched plate with a surface area 2.506 times the cross-sectional area of ​​the reactor (normalized surface area 2.506) was installed downstream of the substrate susceptor as a decomposition promoter. As a result of growing GaN, the growth rate was 100 μm / h and the decomposition rate of NH3 was 78.7%. Almost no parasitic growth of GaN was observed on the reactor wall downstream of the substrate susceptor or on the exhaust piping.

[0045] Example 5 The growth conditions were a growth chamber temperature of 1200°C and a source chamber temperature of 1100°C. The partial pressures of GaO gas, HO gas, NH gas, H gas, and N gas were 0.00107 atm, 0.00046 atm, 0.15748 atm, 0.71850 atm, and 0.12249 atm, respectively, and crystal growth was carried out for one hour. A circular multilayer Mo punched plate with a surface area 5.011 times the cross-sectional area of ​​the reactor (normalized surface area 5.011) was installed downstream of the substrate susceptor as a decomposition promoter. As a result of growing GaN, the growth rate was 118 μm / h and the decomposition rate of NH3 was 89.2%. No parasitic growth of GaN was observed on the reactor wall downstream of the substrate susceptor or on the exhaust piping.

[0046] Example 6 The growth conditions were a growth chamber temperature of 1200°C and a source chamber temperature of 1100°C. The partial pressures of GaO gas, HO gas, NH gas, H gas, and N gas were 0.00105 atm, 0.00048 atm, 0.15749 atm, 0.71849 atm, and 0.12249 atm, respectively, and crystal growth was carried out for one hour. A ring-shaped multilayer Mo punched plate with a surface area 5.011 times the cross-sectional area of ​​the reactor (normalized surface area 5.011) was installed downstream of the substrate susceptor as a decomposition promoter. As a result of growing GaN, the growth rate was 112 μm / h and the decomposition rate of NH3 was 91.7%. No parasitic growth of GaN was observed on the reactor wall downstream of the substrate susceptor or on the exhaust piping.

[0047] (Comparative Example 1) The growth conditions were a growth chamber temperature of 1200°C and a source chamber temperature of 1100°C. The partial pressures of GaO gas, HO gas, NH gas, H gas, and N gas were 0.00105 atm, 0.00048 atm, 0.15749 atm, 0.71849 atm, and 0.12249 atm, respectively, and crystal growth was carried out for one hour. No decomposition promoter was installed. As a result of growing GaN, the growth rate was 98 μm / h and the decomposition rate of NH3 was 10.4%. Parasitic growth of GaN was confirmed on the reactor wall downstream of the substrate susceptor and on the exhaust piping.

[0048] (Summary of Examples and Comparative Examples) FIG. 3 shows a graph illustrating the relationship between the normalized surface area of ​​the decomposition promoting section and the decomposition rate of NH gas. This graph plots the decomposition rates of NH gas obtained from each example and comparative example against the normalized surface area (normalized surface area) of the decomposition promoting section, with each value connected by a straight line. The × plot indicates that parasitic growth of GaN was confirmed on the reactor wall downstream of the substrate susceptor or on the exhaust piping. The ○ plot indicates that almost no parasitic growth of GaN was confirmed. The ● plot indicates that no parasitic growth of GaN was confirmed at all. As can be seen from this graph, in Comparative Example 1, in which the decomposition promoting section was not installed, NH gas was slightly decomposed by thermal decomposition, but the decomposition rate was low. Therefore, parasitic growth of GaN on the reactor wall downstream of the substrate susceptor or on the exhaust piping could not be suppressed.

[0049] On the other hand, in Examples 1 to 6 in which the decomposition promoting section was installed, the decomposition rate of NH3 gas was increased by the decomposition promoting section. Therefore, sufficient decomposition of NH3 gas suppresses parasitic growth of GaN on the reactor wall downstream of the substrate susceptor and on the exhaust piping. Furthermore, as shown in the graph, the decomposition rate can be further increased by increasing the surface area of ​​the decomposition promoting section. In particular, if the normalized surface area of ​​the decomposition promoting section is 5 or more, the occurrence of parasitic growth can be further suppressed. Furthermore, by setting the normalized surface area of ​​the decomposition promoting section to 16.5 or more, the decomposition rate of NH3 gas can be increased to 95% or more, and by setting the normalized surface area to 32 or more, the decomposition rate of NH3 gas can be increased to 100%.

[0050] In addition, the present disclosure includes appropriate combinations of any of the various embodiments and / or examples described above, and can achieve the effects of each embodiment and / or example. [Industrial Applicability]

[0051] The Group III nitride crystal manufacturing apparatus and method according to the present invention have a section for promoting decomposition of unreacted residual gas, which enables unreacted nitrogen-containing gas to be decomposed downstream of the substrate susceptor, thereby suppressing parasitic growth of Group III nitride crystal on the reactor walls and exhaust piping within the growth chamber. [Explanation of symbols]

[0052] 100 raw material chamber 101 Raw material reaction chamber 102 First carrier gas supply port 103 Reactive gas supply pipe 104 Raw Material Boat 105 Starting Group III Element Sources 106 First heater 107 Group III element oxide gas outlet 108 Gas outlet 109 Connecting Pipe 110 Third heater 111 Growth Chamber 112 Third carrier gas supply port 113 Nitrogen-containing gas supply port 114 Second carrier gas supply port 115 Second heater 116 species substrate 117 Substrate susceptor 118 Gas supply port 119 Exhaust vent 120 Decomposition promotion part

Claims

1. a source chamber for generating a Group III oxide gas; a growth chamber in which the Group III element oxide gas and a nitrogen-containing gas supplied from the source chamber are reacted to grow a Group III nitride crystal on a seed substrate; Equipped with the growth chamber has a decomposition promoting section that promotes decomposition of the unreacted nitrogen-element-containing gas between the seed substrate and an exhaust port that exhausts the unreacted Group III oxide gas and the nitrogen-element-containing gas; Group III nitride crystal manufacturing equipment.

2. The decomposition promoting portion contains at least one element selected from the group consisting of Mo, Ni, Fe, Co, Ti, Cr, Zr, Ta, W, and Pt. The Group III nitride crystal manufacturing apparatus according to claim 1 .

3. The total surface area of ​​the decomposition promoting portion is 5 times or more the cross-sectional area of ​​the growth chamber.

3. The Group III nitride crystal manufacturing apparatus according to claim 1 or 2.

4. reacting a Group III element source with a reactive gas to produce a Group III element oxide gas; reacting the Group III element oxide gas with a nitrogen-containing gas to produce a Group III nitride crystal on the seed substrate; decomposing a portion of the unreacted nitrogen-containing gas between the seed substrate and an exhaust port through which the unreacted Group III oxide gas and the nitrogen-containing gas are exhausted; Including, A method for producing a group III nitride crystal.

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