Manufacturing apparatus and wafer tray for Group III nitride crystals

Abstract

The present invention provides a manufacturing apparatus for group III nitride crystals, which includes a wafer tray capable of suppressing the reaction between the wafer tray on which the seed substrate is placed and the seed substrate. [Solution] The apparatus for producing group III nitride crystals has a growth chamber that generates group III nitride crystals on a seed substrate by reacting a group III element oxide gas with a nitrogen element-containing gas, and the growth chamber has a wafer tray on which the seed substrate is placed via a decomposition suppression sheet.

Description

Technical Field

[0001] The present disclosure relates to an apparatus for manufacturing group III nitride crystals and a wafer tray for placing a seed substrate used in the manufacturing apparatus.

Background Art

[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), and next-generation electronic devices such as high-power power transistors mounted on EVs (electric vehicles) and PHVs (plug-in hybrid vehicles).

[0003] As a method for manufacturing group III nitride crystals, an Oxide Vapor Phase Epitaxy (OVPE) method using group III oxides as raw materials is used (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Conventionally, in the method for manufacturing group III nitride crystals, as shown in FIG. 6, a wafer tray 50 for placing a seed substrate 10 has been made of a transition metal such as stainless steel. However, the present inventors have found that there is a problem that the back side of the GaN 10 of the seed substrate is significantly decomposed by the catalytic action of the transition metal constituting the wafer tray 50 in a high-temperature environment for crystal growth. The seed substrate with the decomposed back side cannot be reused repeatedly.

[0006] Furthermore, it was discovered that the transition metals constituting the wafer tray 50 react with the Ga in the seed substrate 10 to form an alloy, causing changes in the shape and physical properties of the wafer tray 50. As a result, the wafer tray 50 cannot be reused repeatedly, meaning its wear cycle is shortened.

[0007] Therefore, the object of this disclosure is to provide a manufacturing apparatus for group III nitride crystals, which includes a wafer tray capable of suppressing the reaction between the wafer tray on which the seed substrate is placed and the seed substrate. [Means for solving the problem]

[0008] The apparatus for producing group III nitride crystals according to this disclosure is a apparatus for producing group III nitride crystals having a growth chamber that generates group III nitride crystals on a seed substrate by reacting a group III element oxide gas with a nitrogen element-containing gas, the growth chamber having a wafer tray on which the seed substrate is placed via a decomposition suppression sheet.

[0009] The wafer tray according to this disclosure is a wafer tray for which a seed substrate is placed via a decomposition suppression sheet in the manufacture of a group III nitride crystal, and the wafer tray has a two-stage structure comprising a first recess for housing the decomposition suppression sheet and a second recess for housing the seed substrate placed via the decomposition suppression sheet, which is continuous with the first recess and connects the first recess to the outside. [Effects of the Invention]

[0010] The apparatus for manufacturing group III nitride crystals according to this disclosure has a wafer tray on which a seed substrate is placed via a decomposition suppression sheet, thereby suppressing the reaction between the wafer tray and the seed substrate. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view showing the cross-sectional configuration of the Group III nitride crystal manufacturing apparatus 200 according to Embodiment 1. [Figure 2] Figure 1 is a schematic cross-sectional view showing the cross-sectional structure of a wafer tray used in a manufacturing apparatus for Group III nitride crystals. [Figure 3] This is a flowchart of the method for producing a group III nitride crystal according to Embodiment 1. [Figure 4A] This is a schematic cross-sectional view showing the cross-sectional structure of a wafer tray used in a manufacturing apparatus for group III nitride crystals according to Embodiment 2. [Figure 4B] This is a schematic plan view showing the relationship between the projection of the first recess and the projection of the second recess as seen from the surface side of the wafer tray in Figure 4A. [Figure 5] Figure 4A is a plan view of the seed substrate placed on the wafer tray, seen from above. [Figure 6] This is a schematic cross-sectional view showing the cross-sectional structure of a wafer tray on which a seed substrate is placed in a conventional method for manufacturing group III nitride crystals. [Modes for carrying out the invention]

[0012] The apparatus for producing group III nitride crystals according to the first embodiment is a apparatus for producing group III nitride crystals having a growth chamber for generating group III nitride crystals on a seed substrate by reacting a group III element oxide gas with a nitrogen element-containing gas, the growth chamber having a wafer tray on which the seed substrate is placed via a decomposition suppression sheet.

[0013] In the second embodiment of the apparatus for manufacturing group III nitride crystals, the decomposition suppression sheet may be provided inside the opening surface of the wafer tray on which the seed substrate is placed, as in the first embodiment.

[0014] In the third embodiment, the apparatus for manufacturing group III nitride crystals may have a two-stage structure in the wafer tray, which includes a first recess for housing a decomposition-inhibiting sheet and a second recess for housing a seed substrate placed via the decomposition-inhibiting sheet, which is continuous with the first recess and connects the first recess to the outside.

[0015] In the manufacturing apparatus for group III nitride crystals according to the fourth aspect, in the above-described third aspect, with respect to the depth x of the first recess of the wafer tray, the depth y of the second recess, the thickness A of the decomposition inhibition sheet, and the thickness B of the seed substrate, the relational expressions of x + y ≤ A + B and x ≤ A may be satisfied.

[0016] In the manufacturing apparatus for group III nitride crystals according to the fifth aspect, in the above-described third or fourth aspect, all of the projections of the first recess viewed from the thickness direction of the wafer tray may be inside the projection of the second recess.

[0017] In the manufacturing apparatus for group III nitride crystals according to the sixth aspect, in any one of the above-described third to fifth aspects, the maximum diameter r of the projection of the first recess viewed from the thickness direction of the wafer tray may satisfy the relational expression of r < R, which is smaller than the minimum diameter R of the seed substrate.

[0018] In the manufacturing apparatus for group III nitride crystals according to the seventh aspect, in any one of the above-described third to sixth aspects, the first recess or the second recess may be provided with a taper on the inner wall surface such that the inner diameter of the first recess or the second recess decreases from the bottom surface side toward the surface side.

[0019] In the manufacturing apparatus for group III nitride crystals according to the eighth aspect, in any one of the above-described first to seventh aspects, the decomposition inhibition sheet may be made of a material selected from the group consisting of SiC, alumina, BN, mullite, SiN, and zirconia.

[0020] The wafer tray according to the ninth aspect is a wafer tray on which a seed substrate is placed in the manufacture of group III nitride crystals, and the seed substrate is placed via a decomposition inhibition sheet provided inside the opening surface on which the seed substrate of the wafer tray is placed.

[0021] The wafer tray according to the tenth aspect, in the above-described ninth aspect, the wafer tray may have a two-stage structure including a first recess for accommodating the decomposition inhibition sheet and a second recess for accommodating the seed substrate placed via the decomposition inhibition sheet and continuous with the first recess to connect the first recess and the outside.

[0022] In the wafer tray according to the 11th aspect, in the 10th aspect described above, with respect to the depth x of the first recess of the wafer tray, the depth y of the second recess, the thickness A of the decomposition suppression sheet, and the thickness B of the seed substrate, the relational expressions of x + y ≤ A + B and x ≤ A may be satisfied.

[0023] In the wafer tray according to the 12th aspect, in the 10th or 11th aspect described above, all of the projections of the first recess as viewed from the thickness direction of the wafer tray may be inside the projection of the second recess.

[0024] In the wafer tray according to the 13th aspect, in any of the 10th to 12th aspects described above, the maximum diameter r of the projection of the first recess as viewed from the thickness direction of the wafer tray may satisfy the relational expression of r < R, which is smaller than the minimum diameter R of the seed substrate.

[0025] In the wafer tray according to the 14th aspect, in any of the 10th to 13th aspects described above, the first recess or the second recess may be provided with a taper on the inner wall surface such that the inner diameter of the first recess or the second recess becomes narrower from the bottom surface side to the surface side with respect to the inner wall surface.

[0026] In the wafer tray according to the 15th aspect, in any of the 9th to 14th aspects described above, the decomposition suppression sheet may be made of a material selected from the group consisting of SiC, alumina, BN, mullite, SiN, and zirconia.

[0027] Hereinafter, a manufacturing apparatus and a manufacturing method for a group III nitride crystal according to an embodiment, and a wafer tray on which a seed substrate is placed in the manufacturing apparatus and the manufacturing method will be described while referring to the drawings. In the following description, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

[0028] (Embodiment 1) [Outline of Manufacturing Apparatus for Group III Nitride Crystal] An overview of the Group III nitride crystal manufacturing apparatus 200 according to Embodiment 1 of this disclosure will be described with reference to the schematic diagram in Figure 1. Figure 1 is a schematic cross-sectional view showing the cross-sectional configuration of the Group III nitride crystal manufacturing apparatus 200 according to Embodiment 1. Note that Figure 1 is a schematic diagram, and the size, proportions, etc. of each component may differ from the actual dimensions.

[0029] The Group III nitride crystal manufacturing apparatus 200 according to this embodiment 1 includes a raw material chamber 100 for generating Group III element oxide gas and a growth chamber 111 for generating Group III nitride crystals on a seed substrate 116.

[0030] A raw material reaction chamber 101 is located within the raw material chamber 100, and a raw material boat 104 containing a starting group III element source 105 is located within the raw material reaction chamber 101. In this 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 to supply 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 transport gas supply port 102. The first transport gas supplied from the first transport gas supply port 102 transports the group III element oxide gas discharged from the group III element oxide gas outlet 107 through the gas outlet 108 and connecting pipe 109 to the growth chamber 111.

[0031] The growth chamber 111 has a gas supply port 118 for supplying group III element oxide gas and a first transport gas, a third transport gas supply port 112, a nitrogen element-containing gas supply port 113, a second transport gas supply port 114, and an exhaust port 119. Inside the growth chamber 111, a wafer tray 120 on which a seed substrate 116 is placed via a decomposition suppression sheet is arranged. The wafer tray 120 is placed on a substrate susceptor 117, which is placed on a rotating shaft 121. A fourth heater 122 is also located below the substrate susceptor 117.

[0032] <Wafer tray> Figure 2 is a schematic cross-sectional view showing the cross-sectional structure of the wafer tray 20 used in the manufacturing apparatus for group III nitride crystals shown in Figure 1. The wafer tray 20 has a seed substrate 10 placed on it via a decomposition suppression sheet 12. Because the seed substrate 10 is placed via the decomposition suppression sheet 12, the reaction between the wafer tray 20 and the seed substrate 10 can be suppressed, and if the group III nitride crystal is GaN, significant decomposition on the back side can be suppressed. In addition, since the transition metal constituting the wafer tray does not react with the Ga of the seed substrate, the lifetime of the wafer tray can be extended. Furthermore, since alloying between the Ga of the seed substrate and the transition metal of the wafer tray can be suppressed, adhesion between the back side of the seed substrate 10 and the surface of the wafer tray can be suppressed. If adhesion occurs between the seed substrate and the wafer tray, it can cause cracking during cooling and when removing the grown crystal. As shown in Figure 2, the wafer tray 20 may also be configured to place the seed substrate 10 on a decomposition-suppressing sheet 12 provided inside the opening 26 on which the seed substrate 10 is placed.

[0033] The wafer tray 20 is composed of materials such as SiC, C (carbon), BN (boron nitride), transition metals, SiO2 (quartz), SiN (silicon nitride), and AlN (aluminum nitride). Furthermore, the wafer tray 20 may have a circular shape when viewed from the thickness direction (upward direction), but is not limited to this; it may also have an elliptical shape, a polygonal shape, or a combination thereof.

[0034] <Decomposition Inhibition Sheet> The decomposition-suppressing sheet 12 may be made of a material selected from the group consisting of, for example, SiC, alumina, BN, mullite, SiN, and zirconia. By making the decomposition-suppressing sheet 12 from these materials, the reaction of the group III nitride crystal with the seed substrate 10 can be suppressed, and the reaction between the seed substrate 10 and the wafer tray 20 can be suppressed by the presence of the decomposition-suppressing sheet 12. The decomposition-suppressing sheet 12 can be replaced as needed. Further, the maximum diameter of the decomposition-inhibiting sheet 12 is the same as or smaller than the diameter of the wafer tray 20.

[0035] Note that the above manufacturing apparatus is an example and is not limited thereto, and any apparatus that can use the above wafer tray may be used.

[0036] <Outline of the method for manufacturing a group III nitride crystal> FIG. 3 is a flowchart of the method for manufacturing a group III nitride crystal according to Embodiment 1. The outline of the method for manufacturing a group III nitride crystal according to Embodiment 1 of the present disclosure will be described with reference to the flowchart of FIG. 3. The method for manufacturing a group III nitride crystal according to Embodiment 1 includes a reactive gas supply step S101, a group III element oxide gas generation step S102, a group III element oxide gas supply step S103, a nitrogen element-containing gas supply step S104, a group III nitride crystal generation step S105, and a residual gas discharge step S106.

[0037] In the reactive gas supply step S101, a 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 be a reducing gas or an oxidizing gas as necessary.

[0038] In the group III element oxide gas generation step S102, 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 element oxide gas.

[0039] In the group III element oxide gas supply step S103, the group III element oxide gas produced in the group III element oxide gas generation step S102 is supplied to the growth chamber 111. The group III element oxide gas is discharged from the raw material reaction chamber 101 through the group III element 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 connection pipe 109, and supplied into the growth chamber 111 from the gas supply port 118.

[0040] In the nitrogen element-containing gas supply step S104, the nitrogen element-containing gas is supplied from the nitrogen element-containing gas supply port 113 to the growth chamber 111.

[0041] In the group III nitride crystal formation step S105, the group III element oxide gas supplied into the growth chamber 111 in the group III element oxide gas supply step S104 and the nitrogen element-containing gas supplied into the growth chamber 111 in the nitrogen element-containing gas supply step are reacted to grow group III nitride crystals on the seed substrate 116.

[0042] In the residual gas discharge step S106, unreacted gas that does not contribute to the formation of group III nitride crystals is discharged from the exhaust port 119 to the outside of the growth chamber 111.

[0043] In the flowchart, the processes are shown with arrows between the processes. However, in actuality, each process shown in the flowchart may be performed simultaneously. The flowchart shows, with arrows, the processes performed upstream to downstream in the group III nitride crystal manufacturing apparatus.

[0044] <Details of the method and apparatus for manufacturing group III nitride crystals> Details of the method for manufacturing group III nitride crystals according to Embodiment 1 will be described. In Embodiment 1, metallic Ga is used as the starting group III element source 105. In the reactive gas supply step S101, the reactive gas is supplied from the reactive gas supply pipe 103 to the raw material reaction chamber 101. In the example of Embodiment 1, since metallic Ga is used as the 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.

[0045] In the Group III element oxide gas generation step S102, the reactive gas supplied to the raw material reaction chamber 101 in the reactive gas supply step S101 reacts with Ga, which is the starting Group III element source 105, to produce 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 outlet 107. The discharged Ga2O gas is mixed with the first transport gas supplied to the raw material chamber 100 from the first transport gas supply port 102 and supplied to the gas outlet 108.

[0046] In this embodiment 1, the raw material chamber 100 is heated by the first heater 106. When heating the raw material chamber 100, it is preferable to set the temperature of the raw material chamber 100 to 800°C or higher, which is higher than the boiling point of Ga2O gas. It is also preferable to set the temperature of the raw material chamber 100 lower than that of the growth chamber 111. As described later, when the growth chamber 111 is heated by the second heater 115, it is preferable to set the temperature of the raw material chamber 100 to, for example, less than 1800°C. The starting group III element source 105 is placed in a raw material boat 104 located in the raw material reaction chamber 101. It is preferable that the raw material boat 104 has a shape that allows for a large 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, it is preferable that the raw material boat 104 has a multi-tiered dish shape.

[0047] There are two main methods for producing Group III element oxide gases: one that reduces the starting Group III element source 105, and another that oxidizes 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 oxidation method, an 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 a Ga source, an In source or an Al source may also be used as the starting Group III element source 105. An inert gas, H2 gas, etc., can be used as the first transport gas.

[0048] In the Group III element oxide gas supply step S103, the Ga2O gas generated in the Group III element oxide gas production step S102 is supplied to the growth chamber 111 via the gas outlet 108, connecting pipe 109, and gas supply port 118. If the temperature of the connecting pipe 109 connecting the raw material chamber 100 and the growth chamber 111 falls below the temperature of the raw material chamber 100, the reverse reaction of the reaction that generates the Group III element oxide gas may occur, and the starting Group III element source 105 may precipitate in the connecting pipe 109. Therefore, it is preferable that the connecting pipe 109 be heated by the third heater 110 so that its temperature does not fall below the temperature of the raw material chamber 100.

[0049] In the nitrogen element-containing gas supply process S104, nitrogen element-containing gas is supplied to the growth chamber 111 from the nitrogen element-containing gas supply port 113. Examples of nitrogen element-containing gases include NH3 gas, NO gas, NO2 gas, N2O gas, N2O4 gas, N2H2 gas, and N2H4 gas.

[0050] In the Group III nitride crystal formation process S105, the raw material gas supplied to the growth chamber 111 via each supply process is reacted to grow Group III nitride crystals on the seed substrate 116. Preferably, the growth chamber 111 is heated to a temperature at which the Group III element oxide gas and the nitrogen element-containing gas react using the second heater 115. At this time, in order to prevent the reverse reaction of the reaction that generates 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 fall below the temperature of the raw material chamber 100 and the temperature of the connecting pipe 109. Preferably, the temperature of the growth chamber 111 heated by the second heater 115 is between 1000°C and 1800°C.

[0051] By mixing the group III element oxide gas supplied to the growth chamber 111 via the group III element oxide supply process S103 and the nitrogen element-containing gas supplied to the growth chamber 111 via the nitrogen element-containing gas supply process S104 upstream of the seed substrate 116, group III nitride crystals can be grown on the seed substrate 116. The above manufacturing method is illustrative, and the apparatus for manufacturing group III nitride crystals according to Embodiment 1 is not limited to the above manufacturing method; any method for manufacturing group III nitride crystals that can use the above wafer tray can be implemented.

[0052] (Embodiment 2) <Wafer tray> Figure 4A is a schematic cross-sectional view showing the cross-sectional structure of the wafer tray 20a according to Embodiment 2. Figure 4B is a schematic plan view showing the relationship between the projection 27 of the first recess 22 and the projection 28 of the second recess 24 as seen from the surface side of the wafer tray 20a in Figure 4A. Figure 5 is a plan view of the seed substrate 10a placed on the wafer tray in Figure 4A as seen from above. As shown in Figure 4A, the wafer tray 20a places the seed substrate 10 on it via a decomposition suppression sheet 12 provided on the inside of the opening surface 26 on which the seed substrate 10 is placed. Furthermore, the wafer tray 20a has a two-tiered structure, comprising a first recess 22 for housing the decomposition-inhibiting sheet 12, and a second recess 24 for housing the seed substrate 10 placed on top of the decomposition-inhibiting sheet 12, which is continuous with the first recess 22 and connects the first recess 22 to the outside. The two-tiered structure of the wafer tray 20a allows for more stable holding of the decomposition-inhibiting sheet 12, and furthermore, by placing the seed substrate 10 on top of it, direct contact between the wafer tray 20a and the seed substrate 10 can be suppressed.

[0053] Furthermore, the depth x of the first recess 22 of the wafer tray 20a, the depth y of the second recess 24, the thickness A of the decomposition-suppressing sheet 12, and the thickness B of the seed substrate 10 may satisfy the relationships x+y≦A+B and x≦A. Since the thickness A of the decomposition-suppressing sheet 12 is greater than the depth x of the first recess 22 (x≦A), when the seed substrate 10 is placed on the decomposition-suppressing sheet 12, the back surface of the seed substrate 10 can be held so as not to contact the step between the first recess 22 and the second recess 24 of the wafer tray 20a. Alternatively, the sum of the thickness A of the decomposition-suppressing sheet 12 and the thickness B of the seed substrate 10 (A+B) may be equal to or greater than the sum of the depth x of the first recess 22 and the depth y of the second recess 24 (x+y) (x+y). This allows the surface of the seed substrate 10 to protrude outward beyond the opening surface 26 defined by the periphery of the wafer tray 20a.

[0054] Furthermore, as shown in Figure 4B, the entire projection 27 of the first recess 22, viewed from the thickness direction of the wafer tray 20a, may be inside the projection 28 of the second recess 24. This prevents the decomposition-suppressing sheet 12 housed in the first recess 22 from being exposed from the seed substrate 10. In Figure 4B, the projections 27 of the first recess 22 and 28 of the second recess 24, viewed from the thickness direction (upward direction), are both circular in shape. However, they are not limited to this and may be elliptical, polygonal, or a combination thereof.

[0055] Also, the maximum diameter r (Fig. 4B) of the projection of the first recess 22 as viewed from the thickness direction (upward) of the wafer tray 20a may satisfy the relational expression r < R, where r is smaller than the minimum diameter R of the seed substrate (Fig. 5). The seed substrate 10a in Fig. 5 shows the case where an orientation flat 14 is provided. In this case, the minimum diameter R is not the diameter that is twice the radius a1. For example, the minimum diameter R is 2a, which is twice the length a from the wafer center to the orientation flat 14. Even in such a case, if the relational expression r < R is satisfied, it is possible to prevent the seed substrate 10a from falling into the first recess 22. Also, it is possible to prevent the decomposition-inhibiting sheet 12 accommodated in the first recess 22 from being exposed. Note that the maximum diameter of the decomposition-inhibiting sheet 12 is the same as or smaller than the maximum diameter r of the first recess 22. Thereby, even when the seed substrate 10a having the orientation flat 14 rotates about the wafer center, it is possible to prevent a part of the decomposition-inhibiting sheet from being exposed from under the seed substrate 10a. Thus, it is possible to prevent a part of the decomposition-inhibiting sheet from being exposed and GaN polycrystals from being deposited.

[0056] Further, the first recess 22 and / or the second recess 24 may be provided with a taper on the inner wall surface such that the inner diameter of the first recess 22 and / or the second recess 24 narrows from the bottom surface side toward the surface side. Thereby, it becomes difficult for the decomposition-inhibiting sheet 12 and / or the seed substrate 10 to jump out from the rotating wafer tray.

Explanation of Reference Numerals

[0057] 10 Seed substrate 12 Decomposition-inhibiting sheet 14 Orientation flat 20, 20a Wafer tray 22 First recess 24 Second recess 26 Opening surface 27 Projection of the first recess 28 Projection of the second recess 50 Wafer tray 100 Raw material chamber 101 Raw material reaction chamber 102 First transfer 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 Rearing Chamber 112 Third Conveyor Gas Supply Port 113 Nitrogen-containing gas supply port 114 Second transport gas supply port 115 Second heater 116 species substrate 117 PCB Susceptor 118 Gas supply port 119 Exhaust vent 120 wafer trays 121 Rotation axis 122 4th Heater 200 Group III Nitride Crystal Manufacturing Apparatus r Maximum diameter of the projection of the first recess Minimum diameter of R-type substrate

Claims

1. A apparatus for producing group III nitride crystals, comprising a growth chamber that generates group III nitride crystals on a seed substrate by reacting a group III element oxide gas with a nitrogen element-containing gas, The growth chamber has a wafer tray on which the seed substrate is placed via a decomposition suppression sheet. A device for manufacturing Group III nitride crystals.

2. The apparatus for manufacturing a group III nitride crystal according to claim 1, wherein the decomposition suppression sheet is provided inside the opening surface of the wafer tray on which the seed substrate is placed.

3. The apparatus for manufacturing a group III nitride crystal according to claim 1 or 2, wherein the wafer tray has a two-stage structure comprising a first recess for accommodating the decomposition suppression sheet and a second recess for accommodating the seed substrate placed via the decomposition suppression sheet, and which is continuous with the first recess and connects the first recess to the outside.

4. Regarding the depth x of the first recess of the wafer tray, the depth y of the second recess, the thickness A of the decomposition suppression sheet, and the thickness B of the seed substrate, x + y ≤ A + B and x ≤ A An apparatus for producing a group III nitride crystal according to claim 3, which satisfies the relationship.

5. The apparatus for manufacturing a group III nitride crystal according to claim 3, wherein the entire projection of the first recess, as viewed from the thickness direction of the wafer tray, lies inside the projection of the second recess.

6. The apparatus for manufacturing a group III nitride crystal according to claim 3, wherein the maximum diameter r of the projection of the first recess as viewed from the thickness direction of the wafer tray is smaller than the minimum diameter R of the seed substrate, satisfying the relationship r < R.

7. The apparatus for producing a group III nitride crystal according to claim 3, wherein the first recess or the second recess has a taper on its inner wall surface such that the inner diameter of the first recess or the second recess narrows from the bottom side towards the surface side.

8. The apparatus for producing group III nitride crystals according to claim 1 or 2, wherein the decomposition-inhibiting sheet is made of a material selected from the group consisting of SiC, alumina, BN, mullite, SiN, and zirconia.

9. A wafer tray for placing a seed substrate in the production of a group III nitride crystal, wherein the seed substrate is placed on the wafer tray via a decomposition-suppressing sheet provided on the inside of the opening surface on which the seed substrate is placed.

10. The wafer tray according to claim 9, having a two-stage structure comprising: a first recess for housing the decomposition-inhibiting sheet; and a second recess for housing the seed substrate placed via the decomposition-inhibiting sheet, which is continuous with the first recess and connects the first recess to the outside.

11. Regarding the depth x of the first recess of the wafer tray, the depth y of the second recess, the thickness A of the decomposition suppression sheet, and the thickness B of the seed substrate, x + y ≤ A + B and x ≤ A A wafer tray according to claim 10 that satisfies the relationship.

12. The wafer tray according to claim 10 or 11, wherein the entire projection of the first recess, as viewed from the thickness direction of the wafer tray, lies inside the projection of the second recess.

13. The wafer tray according to claim 10 or 11, wherein the maximum diameter r of the projection of the first recess as viewed from the thickness direction of the wafer tray is smaller than the minimum diameter R of the seed substrate, satisfying the relationship r < R.

14. The wafer tray according to claim 10 or 11, wherein the inner wall surface of the first recess or the second recess is tapered such that the inner diameter of the first recess or the second recess narrows from the bottom side to the surface side.

15. The wafer tray according to any one of claims 9 to 11, wherein the decomposition-inhibiting sheet is made of a material selected from the group consisting of SiC, alumina, BN, mullite, SiN, and zirconia.

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