Gallium nitride vapor phase growth apparatus and manufacturing method

Abstract

Provided is a vapor-phase epitaxy device for gallium nitride, the device being capable of magnesium doping. The device is a vapor-phase epitaxy device for gallium nitride to be used in a vapor-phase epitaxy method that does not use an organic metal in a gallium raw material. The vapor-phase epitaxy device is equipped with a reaction container. The vapor-phase epitaxy device is equipped with a wafer holder positioned inside the reaction container. The vapor-phase epitaxy device is equipped with a first raw material gas supply pipe for supplying a first raw material gas that contains gallium into the reaction container. The vapor-phase epitaxy device is equipped with a second raw material gas supply pipe for supplying a second raw material gas that contains nitrogen and reacts with the first raw material gas into the reaction container. The vapor-phase epitaxy device is equipped with a third raw material gas supply pipe for supplying a third raw material gas that contains magnesium into the reaction container. In the third raw material gas supply pipe, an oxide of magnesium can be positioned on the supply path. The vapor-phase epitaxy device is equipped with a first heating unit capable of heating the oxide of magnesium positioned in the third raw material gas supply pipe within a first temperature range.

Description

[Technical field]

[0001] This application claims priority to Japanese Patent Application No. 2020-023651, filed on February 14, 2020, the entire contents of which are incorporated herein by reference. This specification discloses a technique relating to a vapor phase growth apparatus and a manufacturing method for gallium nitride. [Background technology]

[0002] There are known compound semiconductor vapor phase epitaxy methods that do not use organic metals as the gallium source, such as HVPE (Halide Vapor Phase Epitaxy) and vapor phase epitaxy methods that use gallium vapor as the source. In these vapor phase epitaxy methods, carbon does not get mixed into the grown crystal. A related technique is disclosed in JP 2002-316892 A. Summary of the Invention [Problem to be solved by the invention]

[0003] In vapor phase epitaxy methods such as HVPE that do not use organic metals as gallium sources, it is difficult to dope with magnesium, which is the most useful p-type acceptor. When using organic metals such as Cp2Mg, they decompose before reaction, and when doping with metallic magnesium, the magnesium evaporates in excess, making it difficult to control the supply amount at a constant level. [Means for solving the problem]

[0004] This specification discloses a gallium nitride vapor phase growth apparatus used in a vapor phase growth method that does not use an organic metal as a gallium source. The vapor phase growth apparatus includes a reaction vessel. The vapor phase growth apparatus includes a wafer holder disposed in the reaction vessel. The vapor phase growth apparatus includes a first source gas supply pipe that supplies a first source gas containing gallium into the reaction vessel. The vapor phase growth apparatus includes a second source gas supply pipe that supplies a second source gas containing nitrogen and reacting with the first source gas into the reaction vessel. The vapor phase growth apparatus includes a third source gas supply pipe that supplies a third source gas containing magnesium into the reaction vessel. The third source gas supply pipe allows an oxide of magnesium to be disposed on a supply path. The vapor phase growth apparatus includes a first heating unit that can heat the oxide of magnesium disposed in the third source gas supply pipe in a first temperature range.

[0005] In the vapor phase growth apparatus of the present specification, the oxide of magnesium is heated in a first temperature range by the first heating unit. The oxide of magnesium decomposes, and a third source gas containing magnesium can be supplied into the reaction vessel. The oxide of magnesium is more stable and less reactive than magnesium metal. Therefore, the supply amount of magnesium in the third source gas can be controlled to be constant. As a result, it becomes possible to perform magnesium doping in a vapor phase growth method that does not use an organic metal as a gallium source.

[0006] The magnesium oxide may be a single crystal.

[0007] The magnesium oxide may be magnesium oxide having a purity of 99% or greater.

[0008] The first temperature range may be between 600°C and 1200°C.

[0009] The first source gas supply pipe may be capable of arranging a solid part containing gallium on a supply path. The vapor phase growth apparatus may further include a second heating part capable of heating the arranged solid part in a second temperature range of 700°C to 1200°C.

[0010] Hydrogen chloride gas or chlorine gas may be supplied to the inlets of the first and third source gas supply pipes. A first source gas containing gallium chloride may be discharged from the outlet of the first source gas supply pipe. A third source gas containing magnesium chloride may be discharged from the outlet of the third source gas supply pipe.

[0011] The second source gas may be a gas containing ammonia.

[0012] The method for producing gallium nitride described in this specification is a method for producing gallium nitride using a vapor phase growth method that does not use an organic metal as a gallium source. The method includes a step of supplying a first source gas containing gallium into a reaction vessel in which a substrate is placed. The method includes a step of supplying a second source gas containing nitrogen and reacting with the first source gas into the reaction vessel. The method includes a step of supplying a third source gas containing magnesium produced by using an oxide of magnesium into the reaction vessel. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a schematic cross-sectional side view of the vapor phase growth apparatus. [Diagram 2] SIMS analysis results and a schematic cross-sectional view of gallium nitride. [Diagram 3] FIG. 1 is a photoluminescence (PL) spectrum. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Configuration of vapor phase growth apparatus> 1 shows a schematic cross-sectional side view of a vapor phase growth apparatus 1 according to this embodiment. The vapor phase growth apparatus 1 is an example of an apparatus configuration for carrying out the HVPE method. The vapor phase growth apparatus 1 includes a reaction vessel 10, a source gas supply pipe 20, and a gas exhaust pipe 71.

[0015] The reaction vessel 10 has a cylindrical shape. The reaction vessel 10 may be made of quartz. A wafer holder 11 is disposed inside the reaction vessel 10. A wafer 13 is held on a wafer holding surface of the wafer holder 11. A rotation shaft 14 is connected to a surface of the wafer holder 11 opposite to the wafer holding surface. An end of the rotation shaft 14 is connected to a drive mechanism 15. This allows the wafer holder 11 to be rotated and moved left and right (±x directions) within the reaction vessel 10.

[0016] The raw gas supply pipe section 20 is connected to the reaction vessel 10. The raw gas supply pipe section 20 includes a first raw gas supply pipe 21, a second raw gas supply pipe 22, a third raw gas supply pipe 23, and specific gas supply pipes 24 and 25. The raw gas supply pipe section 20 has a cylindrical shape. The specific gas supply pipe 25 has a structure in which the second raw gas supply pipe 22, the specific gas supply pipe 24, the first raw gas supply pipe 21, and the third raw gas supply pipe 23 are arranged in this order inside the specific gas supply pipe 25. The supply path of the specific gas supply pipe 25 is formed by a gap between the inner wall of the specific gas supply pipe 25 and the outer wall of the second raw gas supply pipe 22. Similarly, the supply paths of the second raw gas supply pipe 22 and the specific gas supply pipe 24 are also formed by a gap between the inner wall and the outer wall.

[0017] The first raw material gas supply pipe 21 is a pipe for supplying a first raw material gas G1 containing gallium into the reaction vessel 10. Hydrogen chloride (HCl) gas is supplied to the inlet of the first raw material gas supply pipe 21. A quartz boat 41 containing metal gallium 43 is disposed on the path of the first raw material gas supply pipe 21. A heater 32 is disposed outside the raw material gas supply pipe section 20 so as to surround the metal gallium 43. The heater 32 can heat the metal gallium 43 to a temperature range of 700°C to 1200°C. This generates gallium chloride, which can be supplied as the first raw material gas G1 from the outlet (gas supply port) into the reaction vessel 10.

[0018] The second raw material gas supply pipe 22 is a pipe that supplies a second raw material gas G2, which contains nitrogen and reacts with the first raw material gas G1, into the reaction vessel 10. Specifically, the second raw material gas G2 is a gas that contains ammonia (NH3).

[0019] The third raw material gas supply pipe 23 is a pipe for supplying the third raw material gas G3 containing magnesium into the reaction vessel 10. Hydrogen chloride gas is supplied to the inlet of the third raw material gas supply pipe 23. A quartz boat 45 storing magnesium oxide (MgO) 47 is arranged on the path of the third raw material gas supply pipe 23. In this embodiment, the magnesium oxide 47 is a crystal of magnesium oxide with a purity of 99% or more. The specific composition is magnesium oxide (99.9%), aluminum (0.007%), calcium (0.02%), and iron (0.008%). A heater 31 is arranged on the outside of the raw material gas supply pipe section 20 so as to surround the magnesium oxide 47. The heater 31 can heat the magnesium oxide 47 in a temperature range of 600°C to 1200°C. As a result, magnesium chloride is generated and can be supplied into the reaction vessel 10 from the outlet (gas supply port) as the third raw material gas G3. The magnesium oxide 47 may be placed in the same region as the metallic gallium 43 and heated simultaneously by the heater 32 .

[0020] The heating temperature range of magnesium oxide 47 will be described. The substance generated by the reaction between magnesium oxide 47 and hydrogen chloride is mainly MgCl2. Furthermore, from the mass measurement of the MgO raw material before and after the experiment, it was found that the reaction rate of hydrogen chloride was about 5% at 900°C and about 15% at 1200°C. From the above, it can be seen that the higher the heating temperature of magnesium oxide 47, the higher the generation efficiency of magnesium chloride. In other words, it is preferable that the upper limit of the heating temperature of magnesium chloride is as high as possible within a practical range. In addition, considering the durability of the members of the vapor phase growth apparatus 1, the practical upper limit is about 1200°C, which is the upper limit of the use temperature of general-purpose materials such as quartz. Note that the reaction between magnesium oxide and hydrogen chloride is thermodynamically stable, so by using a material with higher heat resistance than quartz, it is possible to raise the heating temperature of magnesium chloride to a temperature higher than 1200°C.

[0021] In addition, examples of methods for improving the efficiency of magnesium chloride generation other than the heating temperature of magnesium chloride include the following methods. (1) A method for increasing the surface area by reducing the particle size of the bulk single crystal of magnesium oxide 47 (e.g., particle size range of 1 μm to 1 mm). (2) A method for increasing the surface area by increasing the volume of the quartz boat 45, which is a reaction vessel, to increase the MgO volume. (3) A method for lengthening the reaction time between magnesium oxide 47 and hydrogen chloride by reducing the flow rate of the third raw material gas G3 (e.g., flow rate range of 0.1 to 10 cm / sec). (4) A method for promoting the reaction by increasing the airtightness of the space where magnesium oxide 47 and hydrogen chloride react. (5) A method of using a gas containing chlorine, which is more reactive with MgO than hydrogen chloride, may be used.

[0022] In this embodiment, two types of magnesium oxide 47 produced by different manufacturing methods are used. The first type of magnesium oxide is bulk single crystal magnesium oxide produced from high purity metallic magnesium. The bulk single crystal magnesium oxide is granular, and the particle size is, for example, in the range of 1 to 10 mm. The single crystal magnesium oxide can be produced by, for example, an electric melting method or a gas phase method (a method of subjecting metallic magnesium vapor to a gas phase oxidation reaction). The second type of magnesium oxide is powder magnesium based on production by firing, and the particle size is smaller than that of bulk single crystal magnesium oxide (for example, the particle size range is 0.1 to 10 μm). An example of the second type of magnesium oxide is magnesium oxide produced by firing magnesium hydroxide. Other examples of the method for producing the second type of magnesium oxide include (1) a spark discharge method, (2) a method of reacting metallic magnesium with oxygen, and (3) a method of reacting carbon dioxide gas with magnesium carbonate slurry to dissolve it as hydrogen carbonate, and then firing the magnesium carbonate recovered by thermal decomposition or the like.

[0023] The supply amount of magnesium supplied from the third source gas supply pipe 23 can be controlled by various parameters. For example, in order to increase the supply amount of magnesium, the heating temperature of the magnesium oxide 47 may be increased, the amount of magnesium oxide 47 placed on the quartz boat 45 may be increased, or the distance between the outlet of the third source gas supply pipe 23 and the wafer 13 may be shortened. In addition, the flow rate of the HCl gas supplied to the first source gas supply pipe 21 may be increased.

[0024] The end position of the outlet side (-x direction side) of the partition between the first raw material gas supply pipe 21 and the third raw material gas supply pipe 23 is defined as end E1. The end position of the outlet side of the second raw material gas supply pipe 22 is defined as end E2. End E1 is located farther from the wafer 13 than end E2. This allows the first raw material gas G1 and the third raw material gas G3 to be mixed, and then the second raw material gas G2 to be mixed. That is, gallium chloride and magnesium chloride can be reacted with ammonia in a state where they are mixed first. The wafer 13 can be uniformly doped with magnesium within the surface.

[0025] The first source gas supply pipe 21 and the third source gas supply pipe 23 are configured as separate lines. This allows the flow rate ratio of the first source gas G1 and the third source gas G3 to be freely set. This makes it possible to freely adjust the amount of magnesium doped into the gallium nitride crystal.

[0026] The specific gas supply pipes 24 and 25 are pipes for supplying a specific gas into the reaction vessel 10. The specific gas is a gas that does not contain oxygen and does not react with the first raw material gas G1 and the second raw material gas G2. Specific examples of the specific gas include gases that contain at least one of hydrogen, nitrogen, helium, neon, argon, and krypton. In this embodiment, a mixed gas of hydrogen and nitrogen is supplied from the specific gas supply pipe 24. Also, nitrogen gas is supplied from the specific gas supply pipe 25.

[0027] A heater 30 is disposed around the outer periphery of the reaction vessel 10 so as to surround the wafer holder 11. The heater 30 is a device that heats the wafer 13 by a hot wall method. This makes it possible to maintain the wafer 13 at a temperature (1050±50°C) sufficient for gallium nitride crystal growth. In addition, the source gas used for the vapor phase growth of gallium nitride is exhausted to a vent line via a gas exhaust pipe 71.

[0028] <Vapor phase growth method> A method for vapor-phase growing gallium nitride crystals on a wafer 13 by using a vapor-phase growth apparatus 1 by HVPE method will be described. An example of gas-phase growth conditions will be listed. As the wafer 13 serving as a support substrate, a wafer having 3 μm of gallium nitride grown on the surface of a sapphire substrate by MOVPE method was prepared. The supply amounts of gallium nitride in the first source gas G1 and ammonia in the second source gas G2 were set to a molar ratio of 1:20. The pressure in the reaction vessel 10 was set to 1000 hPa. Also, the following conditions were used: growth time: 60 [min], heating temperature of the wafer 13: 1070 [°C], heating temperature of gallium metal 43: 850 [°C], heating temperature of magnesium oxide 47: 900 [°C], hydrogen chloride flow rate in the first source gas supply pipe 21: 40 [sccm], hydrogen chloride flow rate in the third source gas supply pipe 23: 5.0 [sccm], flow rate of the second source gas G2 (ammonia): 4 [slm], H2 / (N2+H2) ratio: 0.23.

[0029] By turning on the heater 30, the wafer 13 is heated to 1070 °C. Also, by turning on the heater 32, the gallium metal 43 is heated to 850 °C. Then, the supply of the first source gas G1, the second source gas G2, and the specific gas is started. Thereby, it becomes possible to grow an undoped GaN layer 13a (a gallium nitride crystal layer not doped with magnesium) on the wafer 13.

[0030] When the undoped GaN layer 13a has grown to a predetermined thickness (25 μm), the heater 31 is turned on to further supply the third source gas G3. Thereby, it becomes possible to grow an Mg-doped GaN layer 13b (a gallium nitride crystal layer doped with magnesium) on the undoped GaN layer 13a. When the Mg-doped GaN layer 13b has grown to a predetermined thickness (0.8 μm), the crystal growth is terminated.

[0031] <SIMS analysis results> Figure 2 shows the results of measurement by secondary ion mass spectrometry (SIMS) of gallium nitride crystals grown by the HVPE method of this specification. Figure 2 shows the measurement results before annealing. Figure 2(A) shows concentration profiles P1 to P3 of magnesium, hydrogen, and oxygen in the depth direction, measured using the SIMS method. The vertical axis of Figure 2(A) shows the concentration of each element [atoms / cm 3 The horizontal axis represents the depth [μm] from the surface 13s of the Mg-doped GaN layer 13b. FIG. 2(B) illustrates the structure corresponding to FIG. 2(A). As shown in FIG. 2(B), an Mg-doped GaN layer 13b with a thickness of about 0.8 [μm] is disposed on the surface, and an undoped GaN layer 13a is disposed below it. The magnesium (Mg) concentration of the Mg-doped GaN layer 13b is 1×10 19 ~2×10 19 [atoms / cm 3 On the other hand, the magnesium (Mg) concentration of the undoped GaN layer 13a is in the range of 5×10 14 [atoms / cm 3 ] is below the measurement detection limit Mg_DL. Therefore, it is understood that the HVPE method of this specification can dope Mg at a concentration 10,000 times or more compared to a GaN layer to which Mg is not supplied.

[0032] In addition, attention is focused on the oxygen (O) concentration except for the very surface of the Mg-doped GaN layer 13b and the vicinity of the interface IF between the Mg-doped GaN layer 13b and the undoped GaN layer 13a. The oxygen concentration of the Mg-doped GaN layer 13b is 2×10 16 ~3×10 16 [atoms / cm 3 This is a low value of about 1 / 1000 compared to the Mg concentration of the Mg-doped GaN layer 13b. The detection limit of oxygen, O_DL, is 7×10 15 [atoms / cm 3From the above, it can be seen that even when magnesium oxide containing a high concentration of oxygen (oxygen to Mg ratio of 1:1) is used as the Mg supply source, the concentration of oxygen doped into the Mg-doped GaN layer 13b can be suppressed to a sufficiently low concentration close to the detection limit. Since oxygen functions as a donor in gallium nitride crystals, it is possible to make gallium nitride p-type by reducing the oxygen doping concentration.

[0033] In FIG. 2, the magnesium concentration profile P1 and the hydrogen concentration profile P2 have almost the same shape. This shows that magnesium and hydrogen are bonded at a 1:1 ratio and doped into the gallium nitride crystal. It is known that activation of magnesium is inhibited when hydrogen is bonded to Mg in p-type gallium nitride. For example, in the metalorganic vapor phase epitaxy (MOVPE) method, even in p-type gallium nitride grown using cyclopentadienyl magnesium (Cp2Mg), hydrogen is contained at a concentration equivalent to that of magnesium and is bonded to Mg, so dehydrogenation is required to activate magnesium, which indicates that Mg is incorporated as an acceptor required for p-type semiconductors in the gallium nitride crystal. In the technology described in this specification, as described above, the Mg concentration and H concentration in p-type gallium nitride are approximately the same, and it can be said that the quality is equivalent to that of Mg-doped gallium nitride grown by the MOVPE method.

[0034] <Photoluminescence measurement results> Figure 3 shows room temperature photoluminescence (PL) spectra PS1 and PS2 of a gallium nitride crystal grown by the HVPE method of this specification. The horizontal axis is photon energy [eV], and the vertical axis is PL intensity [arbitrary unit]. A He-Cd laser (wavelength: 325 nm) is used as the excitation light source. The PL spectrum PS1 is the result of measuring the Mg-doped GaN layer 13b before annealing. The PL spectrum PS2 is the result of measuring it after annealing. Annealing was performed in a nitrogen atmosphere at 700°C for 5 minutes.

[0035] The photon energy range R1 of 2.6 to 3.4 eV is the range of donor-acceptor pair emission, which indicates that magnesium has been activated as an acceptor. In the PL spectrum PS1, a peak value exists in the range R1. This shows that the doped magnesium is located at the gallium site and has good crystallinity. Furthermore, a comparison of the PL spectra PS1 and PS2 shows that the PL intensity of the donor-acceptor pair emission increases with annealing. This shows that the activation rate of the p-type impurity (Mg) can be increased by annealing.

[0036] <Hall effect measurement results> The Hall effect of the Mg-doped GaN layer 13b was measured. The specific measurement method is well known, so a detailed description will be omitted. As a result of measuring the Mg-doped GaN layer 13b, the following information was obtained: Conduction type: p-type, carrier concentration (cm -3 ): 1.3×10 17 , mobility (cm 2 / V·sec):9.

[0037] In addition, the activation energy was estimated to be 195 meV based on the temperature dependence of the carrier concentration. This activation energy is comparable to that of p-type gallium nitride fabricated by MOVPE. Therefore, it can be seen that the technology described in this specification can vapor-grow p-type gallium nitride with performance equivalent to that of MOVPE by HVPE.

[0038] <Dependence of manufacturing method of magnesium oxide 47> The ability to vapor-grow p-type gallium nitride was equivalent when using the first type of magnesium oxide (single crystal magnesium oxide) and when using the second type of magnesium oxide (magnesium oxide produced by calcining magnesium hydroxide). However, it was found that the surface morphology of the grown crystal was better when using the first type of magnesium oxide. Therefore, it is considered that the first type of magnesium oxide (single crystal magnesium oxide) is preferable as a Mg-doped raw material for gallium nitride, and that single crystals of magnesium oxide produced by methods other than the thermal decomposition of magnesium hydroxide are preferable. This is considered to be because the first type of magnesium oxide has a higher surface activity than the second type of magnesium oxide. This will be explained below.

[0039] During production (firing), magnesium oxide of the second type forms a stable surface structure with adsorbed compounds such as carbonates, making the surface inactive (stable). The higher the firing temperature of magnesium oxide of the second type, the lower the impurity concentration, but the more inactive the surface becomes. Therefore, it is difficult to react efficiently with HCl gas.

[0040] On the other hand, compared to the second type of magnesium oxide, the first type of magnesium oxide is less likely to form a stable structure on the surface. Therefore, the surface can be activated by easily removing (purifying) the moisture and carbon dioxide adsorbed on the surface through pretreatment at about 600°C. Therefore, the first type of magnesium oxide can react efficiently with HCl gas, which makes it possible to improve the controllability of the concentration of magnesium chloride contained in the third source gas. As a result, it becomes possible to improve the surface morphology.

[0041] <Effects> N-type gallium nitride substrates and semi-insulating gallium nitride substrates are commercially available. However, the fabrication of p-type gallium nitride substrates has not been realized. If p-type gallium nitride substrates could be fabricated, the degree of freedom in the design of various devices would increase and performance would be improved, so there is a demand for the realization of fabrication. In addition, vapor phase epitaxy methods that do not use organic metals as gallium raw materials, such as the HVPE method, have advantages such as a high growth rate and the ability to avoid the problem of carbon contamination that occurs in the MOVPE method, so they are used not only for conventional bulk crystal growth but also for the fabrication of epitaxial layers of power devices. In particular, the HVPE method is an extremely effective means for the growth of drift layers that require low-concentration carrier concentration control and a film thickness of 10 micrometers or more. However, the HVPE method makes it difficult to dope magnesium, which is the most useful p-type acceptor. This is because when doping with metallic magnesium, there are problems such as excessive evaporation of magnesium making it impossible to control the supply amount at a constant level, and reactions with furnace materials such as quartz making it impossible to ensure controllability and productivity, and good crystals cannot be obtained. In addition, when doping is performed using an organic metal such as Cp2Mg, problems occur such as decomposition before reaction and contamination with carbon atoms.

[0042] Therefore, in the vapor phase growth apparatus 1 of this specification, magnesium oxide is used for doping magnesium. That is, by heating magnesium oxide with a heater and pyrolyzing it, a third source gas G3 containing magnesium can be supplied into the reaction vessel. Magnesium oxide is more stable and less reactive than magnesium metal. Therefore, the supply amount of magnesium in the third source gas G3 can be controlled to be constant. As a result, it is possible to grow p-type gallium nitride having good crystallinity using the HVPE method.

[0043] <Modification> Although the embodiments of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

[0044] The magnesium oxide 47 is not limited to high-purity MgO. It is sufficient if it is an oxide of magnesium, and may contain other elements or compounds. It is preferable that it contains an element that does not function as a donor element for gallium nitride.

[0045] The magnesium supply source is not limited to magnesium oxide. For example, other magnesium compounds such as magnesium chloride and magnesium nitride may be used. Magnesium chloride and magnesium nitride are unstable and easily react with moisture in the atmosphere, and are therefore more difficult to handle than magnesium oxide. The other magnesium compounds are preferably compounds that do not contain oxygen, which is a donor element.

[0046] The gas supplied to the inlet of the first raw material gas supply pipe 21 is not limited to hydrogen chloride (HCl) gas. Any gas may be used as long as it can cause the first raw material gas G1 to contain gallium. For example, chlorine (Cl2) gas may be supplied to the inlet. The gas supplied to the inlet of the third raw material gas supply pipe 23 is not limited to hydrogen chloride (HCl) gas. It may be a gas containing Cl, such as chlorine (Cl2) gas, or a gas containing other halogen elements, such as F or Br. Alternatively, it may be a gas containing hydrogen (H2) or hydrogen atoms (H), such as MgH or MgH2.

[0047] The scope of application of the technology described in this specification is not limited to gallium nitride. It can be applied to the crystal growth of various compound semiconductors that can use magnesium as an impurity. For example, it may be applied to AlGaN (aluminum gallium nitride), AlN (aluminum nitride), InN (indium nitride), InGaN (indium gallium nitride), or mixed crystals thereof.

[0048] The numbers and arrangements of the first source gas supply pipe 21 to the third source gas supply pipe 23 described in this specification are merely examples and are not limited to this embodiment. For example, the first source gas supply pipe 21 and the third source gas supply pipe 23 may be integrated.

[0049] The heating temperatures of the wafer 13, the metal gallium 43, and the magnesium oxide 47 are merely examples. For example, the wafer 13 may be heated in the range of 1050°C±100°C.

[0050] Although the first source gas G1 is a gas containing gallium chloride, the present invention is not limited to this. The first source gas G1 may be a gas having any chemical composition as long as it contains gallium. For example, the first source gas G1 may be a gas containing gallium trichloride (GaCl3). Also, for example, the first source gas G1 may be a gas containing simple gallium.

[0051] The technical elements described in this specification or drawings have technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful. [Explanation of symbols]

[0052] 1: Vapor phase growth apparatus 10: Reaction vessel 11: Wafer holder 13: Wafer 20: Source gas supply pipe section 21: First source gas supply pipe 22: Second source gas supply pipe 23: Third source gas supply pipe 30-32: Heater G1: First source gas G2: Second source gas G3: Third source gas

Claims

1. A gallium nitride vapor phase growth apparatus for use in a vapor phase growth method that does not use an organic metal as a gallium source, A reaction vessel; a wafer holder disposed within the reaction vessel; a first source gas supply pipe for supplying a first source gas containing gallium into the reaction vessel; a second source gas supply pipe for supplying a second source gas containing nitrogen and reacting with the first source gas into the reaction vessel; a third source gas supply pipe that supplies a third source gas containing magnesium into the reaction vessel, the third source gas supply pipe having a supply path on which an oxide of magnesium can be disposed; a first heating unit capable of heating the oxide of magnesium disposed in the third raw material gas supply pipe within a first temperature range; A gallium nitride vapor phase growth apparatus equipped with a

2. 2. The gallium nitride vapor phase growth apparatus according to claim 1, wherein the magnesium oxide is a single crystal.

3. 3. The gallium nitride vapor phase growth apparatus according to claim 1, wherein the magnesium oxide has a purity of 99% or more.

4. 4. The gallium nitride vapor phase growth apparatus according to claim 1, wherein the first temperature range is a range of 600°C to 1200°C.

5. the first source gas supply pipe is capable of disposing metallic gallium on a supply path thereof; The gallium nitride vapor phase growth apparatus according to any one of claims 1 to 4, further comprising a second heating unit capable of heating the arranged metallic gallium to a second temperature range of 700°C to 1200°C.

6. Hydrogen chloride gas or chlorine gas is supplied to the inlets of the first source gas supply pipe and the third source gas supply pipe; The first source gas containing gallium chloride is discharged from an outlet of the first source gas supply pipe, 6. The gallium nitride vapor phase growth apparatus according to claim 1, wherein the third source gas containing magnesium chloride is discharged from an outlet of the third source gas supply pipe.

7. 7. The gallium nitride vapor phase growth apparatus according to claim 1, wherein the second source gas is a gas containing ammonia.

8. A method for producing gallium nitride using a vapor phase growth method that does not use an organic metal as a gallium raw material, supplying a first source gas containing gallium into a reaction vessel in which a substrate is placed; supplying a second source gas containing nitrogen and reacting with the first source gas into the reaction vessel; supplying a third source gas containing magnesium produced by using an oxide of magnesium into the reaction vessel; A method for producing gallium nitride comprising the steps of:

9. The method for producing gallium nitride according to claim 8 , wherein the magnesium oxide is a single crystal.

10. The method for producing gallium nitride according to claim 8 or 9, wherein the magnesium oxide has a purity of 99% or more.

11. 11. The method for producing gallium nitride according to claim 8, wherein the third source gas is a gas obtained by heating the magnesium oxide in the range of 600°C to 1200°C.

12. 12. The method for producing gallium nitride according to claim 8, wherein the first source gas is a gas obtained by heating metallic gallium in the range of 700°C to 1200°C.

13. the first source gas is a gas containing gallium chloride, the second source gas is a gas containing ammonia, 13. The method for producing gallium nitride according to claim 8, wherein the third source gas is a gas containing magnesium chloride.

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