Apparatus for producing group III nitride crystals and method for producing group III nitride crystals

Abstract

To provide an apparatus for manufacturing a high quality group III nitride crystal having a small thickness distribution of a grown crystal by reducing the in-plane distribution of the growth rate of the group III nitride crystal.SOLUTION: An apparatus for manufacturing a group III nitride crystal includes: a raw material chamber for producing group III element oxide gas; and a growth chamber 111 for reacting the group III element oxide gas with nitrogen element containing gas to form a group III nitride crystal on a seed substrate 116. When setting: an angle formed by the shortest distance between the tip of a group III element oxide gas supply port 118 and the periphery of the seed substrate and the surface of the seed substrate to θ; the diameter of the group III element oxide gas supply port to S; a distance between the surface of a substrate susceptor 117 and the tip of a first conveyance gas supply port 112 to L1; a distance between the tip of the first conveyance gas supply port and the tip of the group III element oxide gas supply port to M1; and the diameter of the seed substrate to k, those values satisfy a specific conditional expression.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an apparatus for producing Group III nitride crystals and a method for producing 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-output LEDs (light-emitting diodes) and LDs (laser diodes), and next-generation electronic devices such as high-output power transistors mounted on EVs (electric vehicles) and PHVs (plug-in hybrid vehicles), etc. As a method for producing Group III nitride crystals, an oxide vapor phase epitaxy (OVPE) method using Group III oxides as raw materials is used (for example, see Patent Document 1).

[0003] An example of a reaction system in the OVPE method is shown below. (1) Ga is heated, and in this state, H2O gas is introduced. The introduced H2O gas reacts with Ga to generate Ga2O gas (represented by the following formula (I)). (2) Then, NH3 gas is introduced and reacted with the generated Ga2O gas to produce GaN crystals on the seed substrate (reaction 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, the manufacturing method described in Patent Document 1 had a problem in that the growth rate of the grown crystal on the seed substrate had an in-plane distribution when growing the group III nitride crystal. If an in-plane distribution occurs in the growth rate, there will be regions that cannot be cut into wafers when slicing the grown crystal into wafers, which may result in material loss.

[0006] The present disclosure has been made in view of the above-mentioned problems, and has an object to provide a method for producing a high-quality Group III nitride crystal with a narrow film thickness distribution in the grown crystal by reducing the in-plane distribution of the growth rate of the Group III nitride crystal. [Means for solving the problem]

[0007] The Group III nitride crystal manufacturing apparatus of the present disclosure comprises a source chamber and a growth chamber. The source chamber generates a Group III element oxide gas. The growth chamber reacts the Group III element oxide gas supplied from the source chamber with a nitrogen-containing gas to generate a Group III nitride crystal on a seed substrate. The angle formed by the shortest distance between the tip of a Group III element oxide gas supply port that supplies a Group III element oxide gas into the growth chamber and the outer periphery of a seed substrate placed in the growth chamber and the surface of the seed substrate is defined as θ. The diameter of the Group III element oxide gas supply port is defined as S. The distance between the surface of the substrate susceptor that holds the seed substrate, on which the seed substrate is placed, and the tip of a first carrier gas supply port that supplies a first carrier gas into the growth chamber is defined as L1. The distance between the tip of the first carrier gas supply port and the tip of the Group III element oxide gas supply port is defined as M1. The diameter of the seed substrate is defined as k. In this case, the following formulas (1) to (4) are satisfied. 0<θ<90° (1) 0.21≦S / k≦0.35 (2) 1.17≦(L1+M1) / k≦1.55 (3) k = 2 × (L1 + M1) / tan θ + S (4)

[0008] The method for producing a Group III nitride crystal according to the present disclosure uses a Group III nitride crystal production apparatus. The flow rate of the Group III element oxide gas supplied from the Group III element oxide gas supply port is A (m / s). The flow rate of the carrier gas supplied from the first carrier gas supply port is B (m / s). In this case, the following formulas (8) and (9) are satisfied. 1.47≦A≦2.20 (8) 0.50≦B≦0.70 (9) Effect of the Invention

[0009] According to the Group III nitride crystal manufacturing apparatus and Group III nitride crystal manufacturing method of the present disclosure, it is possible to manufacture high-quality Group III nitride crystal with a narrow film thickness distribution in the grown crystal by reducing the in-plane distribution of the growth rate of the Group III nitride crystal. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a conceptual cross-sectional view showing how a wafer is cut out from a grown crystal. [Diagram 2] 1 is a schematic diagram of a Group III nitride crystal manufacturing apparatus according to a first embodiment of the present disclosure. [Diagram 3] 1 is a schematic diagram of a growth chamber in a Group III nitride crystal manufacturing apparatus according to a first embodiment of the present disclosure. [Figure 4] 1 is a schematic diagram of a growth chamber in a Group III nitride crystal manufacturing apparatus according to a first embodiment of the present disclosure. [Diagram 5] 1 is a flowchart showing a method for producing a Group III nitride crystal according to a first embodiment of the present disclosure. [Figure 6] 1A is a graph showing the relationship between S / k and 3σ / μ, and FIG. 1B is a graph showing the relationship between (L1+M1) / k and 3σ / μ in the examples and the comparative examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Background to the Invention> First, the background to the present disclosure will be described.

[0012] Figure 1 shows a conceptual cross-sectional view of cutting a wafer from a grown crystal. When a group III nitride crystal is grown on a seed substrate, if there is an in-plane distribution in the growth rate of the grown crystal on the seed substrate, the thickness of the grown crystal varies in the growth direction. In areas with a slow growth rate, the thickness of the grown crystal is small, and in areas with a fast growth rate, the thickness of the grown crystal is greater than in areas with a slow growth rate. If there is variation in the thickness of the grown crystal, when cutting a wafer with a uniform thickness from the grown crystal, it is necessary to cut the wafer according to the part with the thinnest thickness, which may result in some areas that cannot be made into a wafer, resulting in material loss.

[0013] The present inventors, through extensive research, have discovered that by reducing the in-plane distribution of the growth rate of Group III nitride crystal, it is possible to produce high-quality Group III nitride crystal with a narrow film thickness distribution in the grown crystal. As a result of the above, the Group III nitride crystal manufacturing apparatus and the Group III nitride crystal manufacturing method according to the present disclosure have been achieved.

[0014] A Group III nitride crystal manufacturing apparatus according to a first aspect includes a source chamber for generating a Group III element oxide gas, and a growth chamber for reacting the Group III element oxide gas supplied from the source chamber with a nitrogen-containing gas to generate Group III nitride crystals on a seed substrate, and satisfies the following formulas (1) to (4) when θ is the angle that the shortest distance between an end of a Group III element oxide gas supply port that supplies a Group III element oxide gas into the growth chamber and the outer periphery of a seed substrate placed in the growth chamber makes with the surface of the seed substrate, S is the diameter of the Group III element oxide gas supply port, L1 is the distance between a surface of a substrate susceptor that holds the seed substrate on which the seed substrate is placed and an end of a first carrier gas supply port that supplies a first carrier gas into the growth chamber, M1 is the distance between the end of the first carrier gas supply port and the end of the Group III element oxide gas supply port, and k is the diameter of the seed substrate. 0<θ<90° (1) 0.21≦S / k≦0.35 (2) 1.17≦(L1+M1) / k≦1.55 (3) k = 2 × (L1 + M1) / tan θ + S (4)

[0015] The Group III nitride crystal manufacturing apparatus according to a second aspect may be such that, in the above-mentioned first aspect, the distance M1 and the diameter k further satisfy the following formula (5). 0 <M1 / k≦0.267 ···(5)

[0016] The Group III nitride crystal manufacturing apparatus according to the third aspect, in the above first or second aspect, may further satisfy the following formulas (6) and (7), where Φ is the angle between a vertical portion of a nitrogen-element-containing gas supply port that supplies a nitrogen-element-containing gas into the growth chamber, the vertical portion being perpendicular to the surface of the seed substrate, and an inclined portion inclined from the vertical portion, and γ is the angle between a line connecting the center of the seed substrate and the tip of the nitrogen-element-containing gas supply port, in a cross-sectional view of the growth chamber, and the longitudinal direction of the nitrogen-element-containing gas supply port. 90°<Φ<180° (6) 15°≦γ≦25° (7)

[0017] The Group III nitride crystal manufacturing apparatus according to a fourth aspect may be any of the first to third aspects above, further comprising a second gas supply port for supplying a second carrier gas into the growth chamber, and may satisfy the following formulas (8) and (9) where L2 is the distance between the surface of the substrate susceptor on which the seed substrate is placed and an end of the second carrier gas supply port, and M2 is the distance between the end of the second carrier gas supply port and an end of the Group III element oxide gas supply port. 1.17≦(L2+M2) / k≦1.55 (8) k = 2 × (L2 + M2) / tan θ + S (9)

[0018] A Group III nitride crystal manufacturing apparatus according to a fifth aspect may be configured in such a way that in the above-mentioned fourth aspect, the distance M2 and the diameter k further satisfy the following formula (10). 0 <M2 / k≦0.267 ···(10)

[0019] A sixth aspect of the present invention relates to a method for producing a Group III nitride crystal, which uses the Group III nitride crystal production apparatus according to the first or second aspect, and satisfies the following formulas (11) and (12), where A (m / s) is the flow velocity of the Group III element oxide gas supplied from the Group III element oxide gas supply port, and B (m / s) is the flow velocity of the carrier gas supplied from the first carrier gas supply port. 1.47(m / s)≦A≦2.20(m / s) ···(11) 0.50(m / s)≦B≦0.70(m / s) ···(12)

[0020] A method for producing a Group III nitride crystal according to a seventh aspect is a method for producing a Group III nitride crystal using the Group III nitride crystal production apparatus according to the third aspect, and may satisfy the following formulas (13) to (15), where the flow rate of the Group III element oxide gas supplied from the Group III element oxide gas source is A (m / s), the flow rate of the carrier gas supplied from the first carrier gas supply port is B (m / s), and the flow rate of the nitrogen-element-containing gas supplied from the nitrogen-element-containing gas supply port is C (m / s). 1.47(m / s)≦A≦2.20(m / s) ···(13) 0.50(m / s)≦B≦0.70(m / s) ···(14) 1.00(m / s)≦C≦1.66(m / s) ···(15)

[0021] A method for producing a Group III nitride crystal according to an eighth aspect is a method for producing a Group III nitride crystal using the apparatus for producing a Group III nitride crystal according to the fourth or fifth aspect, and may satisfy the following formulas (16) to (19), where the flow rate of the Group III element oxide gas supplied from the Group III element oxide gas supply port is A (m / s), the flow rate of the carrier gas supplied from the first carrier gas supply port is B (m / s), the flow rate of the nitrogen-element-containing gas supplied from the nitrogen-element-containing gas supply port is C (m / s), and the flow rate of the second carrier gas supplied from the second carrier gas supply port is D (m / s). 1.47(m / s)≦A≦2.20(m / s) ···(16) 0.50(m / s)≦B≦0.70(m / s) ···(17) 1.00 (m / s) ≤ C ≤ 1.66 (m / s) ···(18) 0.15 (m / s) ≤ D ≤ 0.25 (m / s) ···(19)

[0022] Hereinafter, a manufacturing apparatus for a group III nitride crystal and a manufacturing method for a group III nitride crystal according to an embodiment will be described with reference to the accompanying drawings. In the drawings, substantially the same members are denoted by the same reference numerals.

[0023] (Embodiment 1) (Manufacturing Apparatus for Group III Nitride Crystal) First, an overview of a manufacturing apparatus 150 for a group III nitride crystal used in the manufacturing method for a group III nitride crystal according to Embodiment 1 will be described with reference to FIG. 2. Note that in FIG. 2, the sizes, ratios, etc. of the respective constituent members may be different from the actual ones. The manufacturing apparatus 150 for a group III nitride crystal according to Embodiment 1 includes a raw material chamber 100 and a growth chamber 111. The raw material chamber 100 generates a group III element oxide gas. The growth chamber 111 reacts the group III element oxide gas supplied from the raw material chamber 100 with a nitrogen element-containing gas to generate a group III nitride crystal on a seed substrate. Let the angle formed by the shortest distance between the tip of the group III element oxide gas supply port for supplying the group III element oxide gas into the growth chamber 100 and the outer periphery of the seed substrate disposed in the growth chamber with the surface of the seed substrate be θ. Let the diameter of the group III element oxide gas supply port be S. Let the distance between the surface of the substrate susceptor that holds the seed substrate on which the seed substrate is disposed and the tip of the first transfer gas supply port for supplying the first transfer gas into the growth chamber be L1. Let the distance between the tip of the first transfer gas supply port and the tip of the group III element oxide gas supply port be M1. Further, let the diameter of the seed substrate be k. In this case, the following formulas (1) to (4) are satisfied. 0 < θ < 90° ···(1) 0.21 ≤ S / k ≤ 0.35 ···(2) 1.17 ≤ (L1 + M1) / k ≤ 1.55 ···(3) k = 2×(L1 + M1) / tanθ + S···(4)

[0024] According to this Group III nitride crystal manufacturing apparatus, by reducing the in-plane distribution of the growth rate of the Group III nitride crystal, it is possible to manufacture high-quality Group III nitride crystal with a narrow film thickness distribution of the grown crystal.

[0025] Below, each of the components that make up this Group III nitride crystal manufacturing apparatus will be described.

[0026] A raw material reaction chamber 101 is disposed in the raw material chamber 100, and a raw material boat 104 on which a starting Group III element source 105 is placed is disposed in the raw material reaction chamber 101. A reactive gas supply pipe 103 is connected to the raw material reaction chamber 101, which supplies a 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 that discharges the generated Group III element oxide gas. 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.

[0027] In addition, a raw material carrier gas supply port 102 through which a raw material carrier gas is supplied is connected to the raw material chamber 100. The raw material carrier gas supplied from the raw material carrier gas supply port 102 and the Group III element oxide gas discharged from the Group III element oxide gas outlet port 107 flow from the gas outlet port 108 through a connecting pipe 109 to the growth chamber 111, and are supplied into the growth chamber 111 from a gas supply port (Group III element oxide gas supply port) 118 connected to the growth chamber 111.

[0028] The growth chamber 111 has a gas supply port (hereinafter also referred to as a Group III element oxide gas supply port) 118 for supplying a Group III element oxide gas and a raw material carrier gas, a first carrier gas supply port 112, a nitrogen-containing gas supply port 113, a second carrier gas supply port 114, and an exhaust port 119. The growth chamber 111 also includes a substrate susceptor 117 on which a seed substrate 116 is placed.

[0029] In the III-nitride crystal manufacturing apparatus of the present disclosure, the parameters shown in Fig. 3 satisfy the following formula. For the parameters shown in Fig. 3, S is the diameter of the III-nitride gas supply port 118, L1 is the distance between the tip of the first carrier gas supply port 112 and the substrate susceptor 117, and M1 is the distance between the III-nitride gas supply port 118 and the first carrier gas supply port 112. In this case, the case where the III-nitride gas supply port 118 protrudes toward the seed substrate 116 from the first carrier gas supply port is negative (M1<0), the opposite is positive (M1>0), and the case where they are on the same plane is the origin (M1=0). Here, if M1≦0 and the III-nitride gas supply port 118 protrudes toward the seed substrate 116, the concentration of the nitrogen-containing gas at the III-nitride gas supply port 118 in the III-nitride crystal generation step increases, and parasitic growth of the III-nitride crystal may occur at the supply port 118. If the degree of parasitic growth is large, it will cause clogging of Group III element oxide gas supply port 118 or a significant change in gas flow, making it impossible to achieve stable growth of large Group III nitride crystals. Furthermore, the diameter of Group III element oxide gas supply port 118 and seed substrate 116 placed on substrate susceptor 117 is defined as k, and the angle formed by the shortest distance between the outer periphery of seed substrate 116 and the tip of Group III element oxide gas supply port 118 and the surface of seed substrate 116 is defined as θ. In this case, the parameters satisfy the following formulas (1) to (4). 0<θ<90° (1) 0.21≦S / k≦0.35 (2) 1.17≦(L1+M1) / k≦1.55 (3) k=2×(L1+M1) / tanθ+S (4)

[0030] The reason for this will be explained below. First, rearrange equation (4) with respect to θ to obtain the following equation. tanθ=2×(L1 / k+M1 / k) / (1-S / k) ···(4') From the viewpoint of uniforming the thickness of the grown crystal and stably increasing the size, the ranges of 0.2≦S / k≦0.4, 0≦M1 / k≦0.267, and 1.07≦(L1+M1) / k≦1.33 are required. Furthermore, tan θ>0 (0<θ<90°) is required, and in this case, the relationship k>S is derived from formula (4) or formula (4'). This means that the diameter S of the III-group element oxide gas supply port 118 is smaller than the diameter k of the seed substrate 116. In summary, when formulas (1), (2), (3), (4), and (5) are satisfied based on the relationship of formula (4'), a certain amount of uniformity in the thickness of the grown crystal can be ensured. 0<θ<90° (1) 0.21≦S / k≦0.35 (2) 1.17≦(L1+M1) / k≦1.55 (3) k=2×(L1+M1) / tanθ+S (4) 0 <M1 / k≦0.267 ···(5) It is not essential that formula (5) is satisfied, but it is preferable if it is satisfied.

[0031] In addition, the nitrogen-containing gas supply port 113 is preferably configured in a dogleg shape as shown in Fig. 4(a). In this case, the angle Φ between a vertical portion of the nitrogen-containing gas supply port 113 that supplies the nitrogen-containing gas into the growth chamber 111 shown in Fig. 4(a) that is perpendicular to the surface of the seed substrate 116 and an inclined portion inclined from the vertical portion, i.e., the angle Φ of the dogleg portion, preferably satisfies formula (6) from the viewpoint of preventing turbulence during gas mixing on the seed substrate 116. 90°<Φ<180° (6)

[0032] In addition, in the cross-sectional view of the growth chamber 111 shown in FIG. 4(b), the angle γ between the line connecting the center of the seed substrate 116 and the tip of the nitrogen-containing gas supply port 113 and the longitudinal direction of the nitrogen-containing gas supply port 113 preferably satisfies formula (7), from the viewpoint of promoting diffusion of the Group III element oxide gas supplied from the Group III element oxide gas supply port 118 to the growth chamber 111. 15°≦γ≦25° (7) 4(b), angle γ is the angle measured clockwise from the line connecting the center of seed substrate 116 and the tip of nitrogen-containing gas supply port 113, but is not limited to this. Angle γ may be the angle measured counterclockwise from the line connecting the center of seed substrate 116 and the tip of nitrogen-containing gas supply port 113. In this case, if the clockwise direction is positive and the counterclockwise direction is negative, angle γ is expressed as follows: -25°≦γ≦-15° (7-1) may be also possible. In addition, since the longitudinal direction of nitrogen-element-containing gas supply port 113 is deflected at angle γ from the line connecting the center of seed substrate 116 and the tip of nitrogen-element-containing gas supply port 113, a swirling flow is formed, and the diffusion of the Group III element oxide gas can be promoted. Furthermore, the longitudinal direction of the nitrogen-containing gas supply port 113 may be biased in the forward or reverse direction to the rotation direction of the substrate susceptor 117. The rotation direction of the substrate susceptor 117 is preferably the same as the longitudinal bias direction of the nitrogen-containing gas supply port 113 described above, and the mechanism is preferably capable of controlling the rotation up to about 3000 rpm, for example.

[0033] In addition, it is preferable that second gas supply port 114 satisfies the same conditions as those of first gas supply port 112. That is, when the distance between the surface of substrate susceptor 117 on which seed substrate 116 is placed and the tip of second carrier gas supply port 114 is defined as L2, and the distance between the tip of second carrier gas supply port 114 and the tip of Group III element oxide gas supply port 118 is defined as M2, it is preferable that the following formulas (8) and (9) are satisfied. 1.17≦(L2+M2) / k≦1.55 (8) k = 2 × (L2 + M2) / tan θ + S (9) In addition, it is more preferable that the following formula (10) is satisfied. 0 <M2 / k≦0.267 ···(10)

[0034] 4(c), the supply ports 118, 112, 113, and 114 for the gases to the growth chamber 111 are preferably arranged concentrically in a cross-sectional view of the growth chamber 111. Also, as shown in FIG. 4(c), the nitrogen-element-containing gas supply port 113 is preferably arranged in a plurality of concentric circles in a cross-sectional view of the growth chamber 111, and is also preferably configured to pass through the inside of the second carrier gas supply port 114.

[0035] In addition, when the above formula (4) is transformed into an equation expressing tan θ, the above formula (4') becomes tanθ=2×(L1+M1) / (kS)=(2×(L1+M1) / k) / (1-S / k)) It becomes. Next, by substituting the upper and lower limits of (2) and (3) into the above formula to express the upper and lower limits of tan θ, we get (2×1.17) / (1-0.21)≦tan θ≦(2×1.55) / (1-0.35) This can be rearranged as follows: 2.96≦tan θ≦4.77 The range of θ is from 0° to 90°, so the range of θ is 71.3°≦θ≦78.2° Therefore, the upper and lower limit values ​​of θ that satisfy formulas (2), (3), and (4) are obtained.

[0036] <Production method overview> An overview of the III-nitride crystal manufacturing method according to the first embodiment will be described with reference to the flowchart of Fig. 5 and Fig. 2. Fig. 5(a) shows a chronological flowchart of the manufacturing method. Fig. 5(b) shows, as steps, each functional unit from upstream to downstream in a manufacturing apparatus used in this manufacturing method. That is, this III-nitride crystal manufacturing method includes the steps of preparing a seed substrate 116, raising the temperature of the seed substrate 116 in an inert gas atmosphere, raising the temperature of the seed substrate 116 in a nitrogen-element-containing gas atmosphere, supplying a III-element oxide gas and a nitrogen-element-containing gas to grow a III-nitride crystal on the seed substrate 116, lowering the temperature of the III-nitride crystal while suppressing decomposition in the nitrogen-element-containing gas atmosphere, lowering the temperature of the III-nitride crystal in an inert gas atmosphere, and extracting the III-nitride crystal.

[0037] <Seed substrate preparation process> In the seed substrate preparation step of preparing the seed substrate 116, the seed substrate 116 is placed on the substrate susceptor 117.

[0038] <Heating process> In the first embodiment, the method for producing a Group III nitride crystal includes a temperature-raising step, in which the temperature of the growth chamber 111 is raised to 100° C. or higher and lower than 500° C. in an inert gas atmosphere.

[0039] <Decomposition protection temperature increase process> In the first embodiment, the method for producing a III-nitride crystal includes a decomposition protection temperature increase step, in which the temperature of the growth chamber 111 is increased to 500° C. or higher and lower than 1000° C. in an NH3 gas atmosphere.

[0040] <Growth process> In the growth process for growing Group III nitride crystal on the seed substrate 116, a Group III element oxide gas is generated in the source chamber 100 and supplied to the growth chamber 111, and a nitrogen-containing gas is supplied to the growth chamber 111, thereby growing the Group III nitride crystal on the seed substrate 116.

[0041] The growth process 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, and a residual gas discharge step. Each step included in the growth process may be performed simultaneously within the apparatus for manufacturing the group III nitride crystal.

[0042] <Reactive gas supply step> In the reactive gas supply step, a reactive gas is supplied to the raw material reaction chamber 101.

[0043] <Group III element oxide gas generation step> In the group III element oxide gas generation step, a starting group III element source is reacted with a reactive gas (a reducing gas when the starting group III element source is an oxide, and an oxidizing gas when it is a metal) to generate a group III element oxide gas.

[0044] <Group III element oxide gas supply step> In the group III element oxide gas supply step, the group III element oxide gas produced in the group III element oxide gas generation step is supplied to the growth chamber 111.

[0045] <Nitrogen element-containing gas supply step> In the nitrogen element-containing gas supply step, a nitrogen element-containing gas is supplied to the growth chamber 111.

[0046] <Group III nitride crystal generation step> In the group III nitride crystal generation step, the group III element oxide gas supplied into the growth chamber 111 in the group III element 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.

[0047] In this case, in order to uniformize the growth rate distribution within the surface, it is desirable that the flow rate A (m / s) of the gas supplied from the Group III element oxide gas supply port 118, the flow rate B (m / s) of the gas supplied from the first carrier gas supply port 112, the flow rate C (m / s) of the gas supplied from the nitrogen-containing gas supply port 113, and the flow rate D (m / s) of the gas supplied from the second carrier gas supply port 114 satisfy the following formulas (11) to (14). 1.47(m / s)≦A≦2.20(m / s) (11) 0.50(m / s)≦B≦0.70(m / s)···(12) 1.00(m / s)≦C≦1.66(m / s)···(13) 0.15(m / s)≦D≦0.25(m / s)···(14)

[0048] <Residual gas exhaust process> In the residual gas exhaust step, unreacted gas that does not contribute to the formation of Group III nitride crystals is exhausted to the outside of the chamber.

[0049] <Decomposition protection temperature cooling process> In the first embodiment, the method for producing a Group III nitride crystal includes a decomposition protection temperature-reducing step, in which the temperatures of the source chamber 100 and the growth chamber 111 are reduced to 500° C. while supplying NH gas in order to suppress decomposition of the Group III nitride crystal grown on the seed substrate 116.

[0050] <Temperature cooling process> In the first embodiment, the method for producing a Group III nitride crystal includes a temperature-lowering step, in which the temperatures of the source chamber 100 and the growth chamber 111 are lowered to less than 100° C. in an inert gas atmosphere.

[0051] <Removal process> In the first embodiment, the method for producing a Group III nitride crystal includes an unloading step, in which the seed substrate 116 on which the Group III nitride crystal has been grown is unloaded from the growth chamber 111.

[0052] <Details of manufacturing equipment and manufacturing method> The method for producing a Group III nitride crystal according to the first embodiment will be described in detail with reference to FIGS. In the first embodiment, metal Ga is used as the starting group III element source 105, but the present invention is not limited to this, and for example, Al or In may be used. <Seed substrate preparation process> First, prepare the seed substrate 116. For example, gallium nitride, gallium arsenide, silicon, sapphire, silicon carbide, zinc oxide, gallium oxide, and ScAlMgO4 can be used as the seed substrate 116. In this embodiment, gallium nitride is used as the seed substrate 116.

[0053] <Heating process> In the temperature raising step, the temperature of the growth chamber is raised in an inert gas atmosphere to a temperature that does not cause decomposition of the seed substrate 116. In producing Group III nitride crystals by the OVPE method, heating is performed up to about 500° C. in an inert gas (e.g., N2 gas) atmosphere.

[0054] <Decomposition protection temperature increase process> In the decomposition protection heating step, the temperature is raised in a nitrogen-element-containing gas atmosphere while suppressing the decomposition of the seed substrate 116. In the manufacture of Group III nitride crystals by the OVPE method, heating is performed in a state where an inert gas and a nitrogen-element-containing gas, NH3 gas, are mixed up to a temperature of 500° C. or higher and lower than 1200° C. The reason for mixing NH3 is to prevent the seed substrate 116 from decomposing due to the detachment of N atoms.

[0055] <Growth process> In the growth step, a Group III element oxide gas is generated in the source chamber 100 and supplied to the growth chamber 111, and a nitrogen-containing gas is also supplied to the growth chamber 111 to grow a Group III nitride crystal on the seed substrate 116. Specifically, the growth step includes a reactive gas supply step, a Group III element oxide gas generation step, a Group III element oxide gas supply step, a nitrogen-containing gas supply step, a Group III nitride crystal generation step, and a residual gas exhaust step.

[0056] <Reactive gas supply process> 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, as the reactive gas, a reducing gas or an oxidizing gas can be used as necessary. In the present embodiment, since metal Ga is used as the group III element source 105, H2O gas is used as the reactive gas.

[0057] <Group III Element Oxide Gas Supply Step> In the group III element oxide gas generation step, the reactive gas supplied to the raw material reaction chamber 101 in the reactive gas supply step 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 raw material transfer gas supplied from the first transfer gas supply port 102 to the raw material chamber and is supplied to the gas discharge port 108.

[0058] In the present 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 from the viewpoint of the boiling point of Ga2O gas. Also, it is preferable that the temperature of the raw material chamber 100 be lower than that of the growth chamber 111. When the growth chamber is heated by the second heater 115 as described later, it is preferable that the temperature of the raw material chamber 100 be, for example, less than 1800°C.

[0059] The starting group III element source 105 is placed in a raw material boat 104 disposed 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. 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.

[0060] In addition, the methods for generating group III element oxide gas can be broadly 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 oxidation method, 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, CO2 gas, NO gas, N2O gas, NO2 gas) is used as the reactive gas. In addition to the Ga source as the starting group III element source 106, an In source and an Al source can be adopted as the starting group III elements. As the first carrier gas, an inert gas, H2 gas, etc. can be used.

[0061] 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 discharge port 108, the connection pipe 109, and the gas supply port 118. When the temperature of the connection 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 for generating the group III element oxide gas occurs, and the starting Ga source 105 precipitates in the connection pipe 109. Therefore, it is preferable that the connection pipe 109 is heated to a higher temperature than the first heater 106 by the third heater 110 so as not to drop below the temperature of the raw material chamber 100.

[0062] <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, N2H2 gas, and N2H4 gas.

[0063] <Group III nitride crystal generation step> In the III-nitride crystal growth process, the source gases supplied into the growth chamber through each supply process are reacted to grow III-nitride crystals on the seed substrate 116. The growth chamber 111 is preferably heated to a temperature at which the III-element oxide gas and the nitrogen-containing gas react with each other by the second heater 115. At this time, the temperature of the growth chamber 111 is preferably controlled so that it does not drop below the temperature of the source chamber 100 in order to prevent a reverse reaction of the reaction that generates the III-element oxide gas. The temperature of the growth chamber 111 heated by the second heater 115 is preferably 1000° C. or more and 1800° C. or less. In order to suppress temperature fluctuations in the growth chamber 111 due to the Ga2O gas generated in the source chamber 100 and the source carrier gas, it is preferable that the temperatures of the second heater 115 and the third heater 111 are the same.

[0064] The Group III element oxide gas supplied to the growth chamber 111 through a Group III element oxide supplying step and the nitrogen-containing gas supplied to the growth chamber 111 through a nitrogen-containing gas supplying step are mixed upstream of the seed substrate 116, thereby enabling the growth of a Group III nitride crystal on the seed substrate 116. As the second carrier gas, an inert gas, H2 gas, or the like can be used.

[0065] The reactive gas supplying step, the Group III element oxide gas generating step, the Group III element oxide gas supplying step, the nitrogen-containing gas supplying step, the Group III nitride crystal generating step, and the residual gas discharging step, which are included in the growth step, may be performed simultaneously.

[0066] <Residual gas exhaust process> In the residual gas exhaust process, the unreacted Group III element oxide gas and nitrogen element-containing gas, as well as the raw material carrier gas, the second carrier gas, and the first carrier gas are exhausted from the exhaust port 119 .

[0067] <Decomposition protection temperature cooling process> In the decomposition protection temperature-reducing step, the temperature is reduced in a nitrogen-containing gas atmosphere while suppressing the decomposition of the Group III nitride crystal. In the production of Group III nitride crystals by the OVPE method, the temperature is reduced to 500°C or lower in a state in which an inert gas and a nitrogen-containing gas, NH3 gas, are mixed.

[0068] <Temperature cooling process> In the temperature-lowering step, the temperature is lowered in an inert gas atmosphere to a temperature at which the Group III nitride crystal can be removed from the growth chamber.

[0069] <Removal process> In the first embodiment, seed substrate 116 on which the Group III nitride crystal has grown is removed from growth chamber 111 after the temperature lowering step.

[0070] (Summary of Examples and Comparative Examples) Group III nitride crystals were grown using the Group III nitride crystal manufacturing apparatus shown in Figure 2. 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, which is a reactive gas, and Ga2O gas was used as the Group III element oxide gas. NH3 gas was used as the nitrogen element-containing gas, and a mixture of H2 gas and N2 gas was used as the raw material carrier gas, second carrier gas, and first carrier gas. A GaN free-standing substrate was used as the seed substrate. The flow rates of each gas were supplied so as to fall within the ranges of equations (11), (12), (13), and (14).

[0071] Example 1 The growth conditions were a growth chamber temperature of about 1200°C and a source chamber temperature of about 1100°C. In this example, k was 150 mm, S was 45 mm, L1 and L2 were 160 mm, and M1 and M2 were 40 mm. In this case, the ranges are as shown in formulas (2), (5), and (3). In addition, θ is 75.29° for the relationship of formula (4') to be established within the range of formula (1).

[0072] As a result of growing GaN, the average growth rate μ of GaN grown on the seed substrate was 62.8 μm / h, and the variation in the growth rate was 4.68% when expressed as 3σ / μ, where σ is the standard deviation of the growth rate in the plane. In addition, the amount of parasitic growth of GaN on the Group III element oxide gas supply port and carrier gas supply port was extremely small.

[0073] Comparative Example 1 The growth conditions were a growth chamber temperature of about 1200°C and a source chamber temperature of about 1100°C. In this example, k was set to 100 mm, S to 30 mm, L1 and L2 to 160 mm, and M1 and M2 to 0 mm. In this case, the range of formula (VI) is satisfied, but M1 / k=0, M2 / k=0, (L1+M1) / k=1.60, and (L2+M2) / k=1.60, which are outside the ranges of formulas (5) and (3). In addition, θ for the relationship of formula (4') to be satisfied within the range of formula (1) is 83.46°.

[0074] As a result of growing GaN, the average growth rate of GaN grown on the seed substrate was 48.25 μm / h, and the variation of the growth rate of GaN on the substrate was 37.40% at 3σ / μ. In addition, a large amount of parasitic growth of GaN was confirmed on the Group III element oxide gas supply port and the carrier gas supply port.

[0075] Comparative Example 2 The growth conditions were a growth chamber temperature of about 1200°C and a source chamber temperature of about 1100°C. In this example, k was set to 100 mm, S to 30 mm, L1 and L2 to 100 mm, and M1 and M2 to 0 mm. In this case, the range of formula (VI) is satisfied, but M1 / k=0, M2 / k=0, (L1+M1) / k=1.00, and (L2+M2) / k=1.00, which are outside the ranges of formulas (5) and (3). In addition, θ for formula (4') to be satisfied within the range of formula (1) is 79.61°.

[0076] As a result of growing GaN, the average growth rate of GaN grown on the seed substrate was 67.75 μm / h, and the variation of the growth rate of GaN on the substrate was 58.19% at 3σ / μ. In addition, a large amount of parasitic growth of GaN was confirmed on the Group III element oxide gas supply port and the carrier gas supply port.

[0077] Comparative Example 3 The growth conditions were a growth chamber temperature of about 1200°C and a source chamber temperature of about 1100°C. In this example, k was set to 150 mm, S to 67 mm, L1 and L2 to 160 mm, and M1 and M2 to 0 mm. In this case, the range of formula (3) is satisfied, but S / k=0.4467, M1 / k=0, and M2 / k=0, which are outside the ranges of formulas (2) and (5). In addition, θ for formula (4') to be satisfied within the range of formula (1) is 75.46°.

[0078] As a result of growing GaN, the average growth rate of GaN grown on the seed substrate was 70.6 μm / h, and the variation of the growth rate of GaN on the substrate was 76.18% at 3σ / μ. In addition, a large amount of parasitic growth of GaN was confirmed on the Group III element oxide gas supply port and the carrier gas supply port.

[0079] Comparative Example 4 The growth conditions were a growth chamber temperature of about 1200°C and a source chamber temperature of about 1100°C. In this example, k was set to 150 mm, S to 20 mm, L1 and L2 to 160 mm, and M1 and M2 to 0 mm. In this case, the range of formula (3) is satisfied, but S / k=0.1333, M1 / k=0, and M2 / k=0, which are outside the ranges of formulas (2) and (5). In addition, θ for formula (4') to be satisfied within the range of formula (1) is 67.89°. As a result of growing GaN, the average growth rate of GaN grown on the seed substrate was 80.0 μm / h, and the variation of the growth rate of GaN on the substrate was 50.48% at 3σ / μ. In addition, a large amount of parasitic growth of GaN was confirmed on the Group III element oxide gas supply port and the carrier gas supply port.

[0080] (Summary of Examples and Comparative Examples) Table 1 shows a list of the results of the examples and comparative examples. In Example 1, which satisfies all of formulas (2), (5), and (3), the distribution of the film thickness is 4.68% in 3σ / μ, and extremely uniform bulk growth is realized, and the amount of parasitic GaN growth at the Group III element oxide gas supply port is extremely small. FIG. 6 also shows the results of the examples and comparative examples in the form of a graph. As can be seen from this, in order to make the in-plane growth rate variation 3σ / k 30% or less, S / k needs to be 0.21 to 0.35 and (L+M) / k needs to be 1.17 to 1.55. In order to make 3σ / k 20% or less, S / k needs to be 0.245 to 0.33 and (L+M) / k needs to be 1.23 to 1.45. Furthermore, in order to make 3σ / k 10% or less, S / k must be 0.28 or more and 0.31 or less, and (L+M) / k must be 1.30 or more and 1.38 or less.

[0081] [Table 1]

[0082] For these reasons, by satisfying the desired range according to the present invention, the film thickness distribution of the grown crystal is uniform within the plane, and high-quality III-nitride crystal can be produced.

[0083] 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. [Explanation of symbols]

[0084] 100 Raw Material Chamber 101 Raw material reaction chamber 102 Raw material carrier gas supply port 103 Reactive gas supply pipe 104 Raw Material Boat 105 Starting Ga source 106 First heater 107 Group III element oxide gas outlet 108 Group III element oxide gas and carrier gas outlet 109 Connecting Pipe 110 3rd heater 111 Growth Chamber 112 First 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 Group III element oxide gas supply port 119 Exhaust vent 150 III-nitride crystal manufacturing equipment

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 with each other to produce a Group III nitride crystal on a seed substrate; Equipped with an angle θ is defined as a shortest distance between a tip of a Group III element oxide gas supply port for supplying the Group III element oxide gas into the growth chamber and an outer periphery of the seed substrate disposed in the growth chamber and a surface of the seed substrate; The diameter of the Group III element oxide gas supply port is S, The distance between the surface of the substrate susceptor on which the seed substrate is placed and the tip of a first carrier gas supply port for supplying a first carrier gas into the growth chamber is defined as L. 1 year, The distance between the tip of the first carrier gas supply port and the tip of the Group III element oxide gas supply port is M 1 year, When the diameter of the seed substrate is k, The following formulas (1) to (4) are satisfied: 0<θ<90°...(1) 0.21≦S / k≦0.35 (2) 1.17≦(L 1 +M 1 ) / k≦1.55 ・・・(3) k=2×(L 1 +M 1 ) / tanθ+S・・・(4) A manufacturing apparatus for III-nitride crystals.

2. The distance M 1 And the diameter k further satisfies the following formula (5): 0<M 1 / k≦0.267 ・・・(5) 2. An apparatus for producing a Group III nitride crystal according to claim 1.

3. an angle between a vertical portion of a nitrogen-containing gas supply port that supplies the nitrogen-containing gas into the growth chamber, the vertical portion being perpendicular to the surface of the seed substrate, and an inclined portion inclined from the vertical portion is defined as Φ; When viewed in cross section of the growth chamber, an angle formed between a line connecting the center of the seed substrate and the tip of the nitrogen-containing gas supply port and a longitudinal direction of the nitrogen-containing gas supply port is defined as γ. Further satisfying the following formulas (6) and (7): 90°<Φ<180°...(6) 15°≦γ≦25° (7) 3. An apparatus for producing a Group III nitride crystal according to claim 1 or 2.

4. a second gas supply port for supplying a second carrier gas into the growth chamber; The distance between the surface of the substrate susceptor on which the seed substrate is placed and the tip of the second carrier gas supply port is defined as L 2 year, The distance between the tip of the second carrier gas supply port and the tip of the Group III element oxide gas supply port is set to M 2 In this case, Satisfy the following formulas (8) and (9): 1.17≦(L 2 +M 2 ) / k≦1.55 ・・・(8) k=2×(L 2 +M 2 ) / tanθ+S・・・(9) 4. The Group III nitride crystal manufacturing apparatus according to claim 1.

5. The distance M 2 And the diameter k further satisfies the following formula (10): 0<M 2 / k≦0.267 ・・・(10) 5. An apparatus for producing a Group III nitride crystal according to claim 4.

6. A method for producing a Group III nitride crystal using the Group III nitride crystal production apparatus according to claim 1 or 2, comprising: the flow velocity of the Group III element oxide gas supplied from the Group III element oxide gas supply source is A (m / s); When the flow velocity of the carrier gas supplied from the first carrier gas supply port is B (m / s), The following formulas (11) and (12) are satisfied. 1.47 (m / s)≦A≦2.20 (m / s) (11) 0.50 (m / s)≦B≦0.70 (m / s) (12) A method for producing a Group III nitride crystal.

7. A method for producing a Group III nitride crystal using the Group III nitride crystal production apparatus according to claim 3, comprising the steps of: the flow velocity of the Group III element oxide gas supplied from the Group III element oxide gas supply source is A (m / s); The flow velocity of the carrier gas supplied from the first carrier gas supply port is B (m / s), When the flow velocity of the nitrogen-containing gas supplied from the nitrogen-containing gas supply port is C (m / s), The following formulas (13) to (15) are satisfied. 1.47 (m / s)≦A≦2.20 (m / s) (13) 0.50 (m / s)≦B≦0.70 (m / s) (14) 1.00 (m / s)≦C≦1.66 (m / s) (15) A method for producing a Group III nitride crystal.

8. A method for producing a Group III nitride crystal using the Group III nitride crystal production apparatus according to claim 4 or 5, comprising: the flow velocity of the Group III element oxide gas supplied from the Group III element oxide gas supply source is A (m / s); The flow velocity of the carrier gas supplied from the first carrier gas supply port is B (m / s), The flow velocity of the nitrogen-containing gas supplied from the nitrogen-containing gas supply port is C (m / s), When the flow velocity of the second carrier gas supplied from the second carrier gas supply port is D (m / s), The following formulas (16) to (19) are satisfied. 1.47 (m / s)≦A≦2.20 (m / s) (16) 0.50 (m / s)≦B≦0.70 (m / s) (17) 1.00 (m / s)≦C≦1.66 (m / s) (18) 0.15 (m / s)≦D≦0.25 (m / s) (19) A method for producing a Group III nitride crystal.

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