Gallium nitride particles and method for producing the same

Abstract

To provide gallium nitride particles with low oxygen content and high purity, which are suitable for raw materials and sintered bodies.SOLUTION: Gallium nitride particles are characterized by an oxygen content of 0.5 at% or less and a total impurity content of less than 10 wt ppm of elements Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, Cd.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to gallium nitride particles used as a raw material for a gallium nitride sintered body used in producing a gallium nitride thin film by sputtering. [Background technology]

[0002] Gallium nitride has attracted attention as a raw material for the light-emitting layer of blue light-emitting diodes (LEDs) and blue laser diodes (LDs). In recent years, it has been used in a variety of applications, such as white LEDs and blue LDs, in the form of thin films or substrates. It is also attracting attention as a material for future applications such as power devices.

[0003] One method for producing gallium nitride thin films is sputtering using a target. Gallium nitride sputtering targets are made by molding or sintering gallium nitride powder. However, if the gallium nitride powder, which is the raw material for the target, has a high oxygen content, the resulting gallium nitride film will contain a lot of oxygen, resulting in poor crystallinity. Furthermore, attempts to reduce the oxygen content have traditionally resulted in larger particle sizes, and sintered bodies exceeding 120 mm in diameter are particularly susceptible to insufficient strength and shape retention. Furthermore, when used in various devices, the raw material gallium nitride sputtering target must be highly pure in order to control the amount of various dopants, but it has not been possible to produce such sintered bodies until now.

[0004] A commonly known method for producing gallium nitride powder is to heat metallic gallium in an ammonia gas stream to between 1000°C and 1200°C to obtain polycrystalline gallium nitride. In this method, gallium nitride is formed on the surface of the metallic gallium, which prevents contact between the internal metallic gallium and ammonia gas, preventing further nitridation. In addition, metallic gallium has a low melting point of approximately 30°C, so it is in liquid form during the nitriding process, leaving a small reactive surface area, making it difficult for the reaction to proceed.

[0005] Another method involves heating gallium oxide in an ammonia gas atmosphere to obtain gallium nitride (see, for example, Patent Documents 1 and 2). In this method, the obtained substance is identified as gallium nitride using fluorescent X-rays and an electron probe microanalyzer (EPMA), but there is no mention of the trace amounts of impurities in the powder, nor is there any detailed description of the ammonia gas atmosphere.

[0006] Furthermore, there is another method for obtaining gallium nitride powder (see, for example, Patent Document 3), but with this technique it is difficult to obtain powder with an oxygen content below a certain level.

[0007] Patent Document 4 discloses a technology for obtaining gallium nitride powder by nitriding GaO gas obtained by vaporizing gallium oxide in a reducing atmosphere, but the gallium source gas contains a large amount of oxygen, and it was not possible to obtain powder that was both low in oxygen and highly pure.

[0008] Furthermore, Patent Document 5 discloses a technique relating to gallium nitride particles with a low oxygen content, but since the particles are not precipitated after being vaporized, a powder with high purity cannot be obtained. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-29713 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-198978 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-129568 [Patent Document 4] Japanese Patent Application Laid-Open No. 2009-234800 [Patent Document 5] WO2018-230663 publication Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a low-oxygen, high-density, high-purity gallium nitride sputtering target and gallium nitride particles with a low oxygen content and few impurities that can be used to produce gallium nitride single crystals. [Means for solving the problem]

[0011] In light of this background, the inventors conducted extensive research and, as a result, investigated the nitriding conditions and discovered the conditions for obtaining gallium nitride particles with high purity and low oxygen content, thereby completing the present invention.

[0012] That is, the present invention has the following aspects [1] to [8].

[0013] (1) Gallium nitride particles characterized by an oxygen content of 0.5 at% or less and a total impurity content of the elements Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd of less than 10 wtppm.

[0014] (2) Gallium nitride particles according to (1), characterized in that the total amount of impurities of Mg and Si is less than 5 wtppm.

[0015] (3) Gallium nitride particles according to (1) or (2), characterized in that the total impurity amount of Si is less than 1 wtppm.

[0016] (4) Gallium nitride particles according to any one of (1) to (3), characterized in that the oxygen content is 0.1 at % or less.

[0017] (5) A method for producing gallium nitride particles according to any one of (1) to (4), characterized in that after nitriding gallium oxide as a starting material, ammonia gas for transportation heated to a temperature of 1150°C or more and 1300°C or less is introduced into the nitriding-treated gallium oxide heated to a temperature of 1150°C or more and 1300°C or less as a precipitation treatment, and the vaporized gallium nitride is precipitated by introducing ammonia gas for precipitation heated to a temperature of 900°C or more and 1100°C or less.

[0018] (6) A sintered body made of gallium nitride particles according to any one of (1) to (4).

[0019] (7) A sputtering target made using the sintered body according to (6).

[0020] (8) A thin film obtained by using the sputtering target according to (7).

[0021] The present invention will be described in detail below, but the present invention is not limited to the following embodiments.

[0022] The gallium nitride particles of the present invention are characterized by an oxygen content of 0.5 at% or less, preferably 0.2 at% or less, and more preferably 0.1 at% or less, which makes it possible to reduce the oxygen content in the gallium nitride sintered body after sintering.

[0023] The gallium nitride particles of the present invention are characterized by having a total impurity content of Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd of less than 10 wtppm. These elements are contained in gallium nitride to make it a p-type or n-type semiconductor, and in order to control the content, they must not be contained in the gallium nitride particles, which are the raw material. The total impurity content is preferably 5 wtppm or less, more preferably 3 wtppm or less, even more preferably 1 ppm or less, and even more preferably 0.5 ppm or less.

[0024] Among these impurities, the total amount of Mg and Si, which have a high activation rate, is preferably 5 wtppm or less, more preferably 2 wtppm or less, even more preferably 1 wtppm or less, and even more preferably 0.5 ppm or less. Furthermore, the amount of Si impurity is preferably 1 wtppm or less, and even more preferably 0.5 ppm or less.

[0025] The gallium nitride particles of the present invention preferably have a 50% particle size of approximately spherical primary particles of 5 μm or less, more preferably 3 μm or less, allowing the approximately spherical gallium nitride particles to fully exhibit their low-oxygen and high-sinterability effects.

[0026] The gallium nitride particles of the present invention preferably have an average particle size of 20 μm or less, more preferably 1 μm to 20 μm, even more preferably 1 μm to 10 μm, and most preferably 1 μm to 8 μm, which results in particles suitable for densification during firing.

[0027] Furthermore, the gallium nitride particles of the present invention preferably have a 50% particle size of the primary particles of 5 μm or more and 50 μm or less, preferably 7 μm or more and 40 μm or less, and more preferably 10 μm or more and 30 μm or less. By setting the particle size to 5 μm or more, it is possible to reduce the influence of surface oxidation, further reduce the amount of oxygen, and improve the density during sintering. Furthermore, since the surface layer is small, it is possible to suppress to some extent the decomposition that would normally occur at high temperatures, and it is also possible to increase the sintering temperature. By setting the particle size to 50 μm or less, the surface is large, making it easier to proceed with sintering. The particle size here refers to the 50% particle size in terms of the area of the primary particles as observed with a scanning electron microscope or the like.

[0028] The shape of the gallium nitride of the present invention is preferably plate-like for large-diameter particles. This is because, unlike normal crystal growth that starts from a substrate, growth starts from the particle, so plate-like lateral growth occurs primarily rather than columnar c-axis growth. Because the material is ultimately sintered into a plate shape, a plate shape is preferable to a columnar shape.

[0029] The loose bulk density is 1.2 g / cm 3 Preferably, it is greater than 1.4 g / cm 3 greater than 1.6 g / cm 3This allows for high packing properties, makes it easier to densify during firing, and when used as a raw material for single crystals, reduces the volume occupied and allows for the use of smaller containers.

[0030] Next, a method for producing the gallium nitride particles of the present invention will be described.

[0031] The method for producing gallium nitride particles of the present invention relates to a method for obtaining gallium nitride particles by nitriding gallium oxide as a starting material, introducing ammonia gas for transportation heated to a temperature of 1150°C or higher and 1300°C or lower as a precipitation treatment into the gallium oxide that has been nitrided and heated to a temperature of 1150°C or higher and 1300°C or lower, and precipitating the vaporized gallium nitride by introducing ammonia gas for precipitation heated to a temperature of 900°C or higher and 1100°C or lower.

[0032] The purity of the gallium oxide used in the present invention is preferably 4N (99.99%) or higher, and more preferably 5N (99.999%) or higher. By increasing the purity of the gallium oxide used, it becomes possible to obtain gallium nitride particles with high purity.

[0033] The nitriding temperature of gallium oxide when nitriding is performed is preferably 1000° C. or higher and 1100° C. or lower, and more preferably 1025° C. or higher and 1075° C. By performing the treatment within this range, it is possible to nitride gallium oxide while suppressing vaporization.

[0034] The treatment time for the nitriding treatment is preferably 3 hours or more, more preferably 6 hours or more, in order to achieve complete nitriding. Since decomposition does not progress significantly at the above nitriding temperatures, the yield does not change significantly, but a treatment time of 60 hours or less is preferable in terms of the balance between productivity and the effect of nitriding.

[0035] The flow rate of ammonia gas during the nitriding treatment is such that the reaction proceeds without decomposition to gallium, so that the molar ratio of nitrogen in the ammonia gas to gallium in the gallium oxide is preferably 5 or more, more preferably 10 or more. Furthermore, the amount of ammonia gas reacted per hour is preferably 1 molar or more relative to the amount of gallium introduced, more preferably 1.5 molar or more, and particularly preferably 2 molar or more. By setting the ammonia gas flow rate during the nitriding treatment within the above range, it becomes possible to suppress the vaporization reaction of gallium oxide and the decomposition reaction of the synthesized gallium nitride.

[0036] After the nitriding treatment, ammonia gas for transportation heated to a temperature of 1150°C or higher and 1300°C or lower is introduced into the gallium oxide that has been subjected to the nitriding treatment and heated to a temperature of 1150°C or higher and 1300°C or lower as a precipitation treatment. The temperature of the ammonia gas for transportation is preferably 1150°C or higher and 1200°C or lower. By treating within this range, it becomes possible to obtain highly purified and vaporized gallium nitride particles without decomposing into nitrogen and gallium. If ammonia gas for transportation is not used, gallium nitride will decompose into nitrogen and gallium, and the desired product will not be obtained.

[0037] The time for introducing ammonia gas for transportation into gallium oxide that has been subjected to nitriding treatment and heated to 1150°C or higher and 1300°C or lower is preferably 3 hours or longer, and more preferably 6 hours or longer. If the time is shorter than this time, the amount of precipitation will be small, resulting in a low yield, and particle growth will not progress, and oxidation of the particle surface will progress during removal, making it difficult to obtain gallium nitride particles with the desired oxygen content. The upper limit is preferably 30 hours or shorter, and more preferably 20 hours or shorter. If the time exceeds this time, the particles will grow too large and will not become particles suitable for the intended use.

[0038] For the deposition process, ammonia gas for transportation is introduced into the nitrided gallium oxide, and then deposition ammonia gas heated to 900°C to 1100°C is further introduced into the vaporized gallium nitride to deposit it. The introduction of deposition ammonia gas enables the deposition of vaporized gallium nitride particles. The key to deposition is the use of ammonia gas. Simply lowering the temperature inside the furnace results in preferential deposition on the furnace walls, resulting in the inclusion of many impurities from the furnace material. Furthermore, the absence of a reactive gas such as ammonia gas during deposition can result in the deposition of metallic gallium or gallium oxide due to a lack of nitrogen. Furthermore, the ammonia gas used for deposition must be sprayed onto the deposition site within 30 seconds after reaching the specified temperature. If ammonia gas is exposed to temperatures above 1000°C for a long period of time, it dissociates into nitrogen and hydrogen, preventing the generation of the active species (e.g., NH2) necessary for reaction with gallium, preventing the deposition reaction from proceeding. At even lower temperatures, the particles become finer and the oxygen content cannot be maintained.

[0039] By setting the temperature of the ammonia gas for precipitation as described above, particle growth is possible without further decomposition. In this way, by vaporizing gallium nitride particles and then precipitating and growing them, the purity of the gallium nitride particles can be increased. Furthermore, to increase purity, it is preferable that the deposition site is free of substrates, seed crystals, etc. for the gallium nitride particles. The presence of substrates, seed crystals, etc. introduces oxygen and impurities, making it difficult to obtain high-purity gallium nitride particles. Furthermore, when grown on a substrate, the particles do not grow into particles, requiring subsequent processes such as pulverization, which can lead to impurity contamination. The particles precipitated in this way have a high bulk density, making them more useful as materials for producing sintered bodies and synthesizing single crystals.

[0040] The position where the vaporized gallium nitride particles are deposited can be freely set by the ammonia gas inlet. An example of the introduction method is shown in Figure 1.

[0041] The precipitation treatment time is preferably 3 hours or more, and more preferably 6 hours or more. If the time is shorter, the amount of precipitation will be small, resulting in a low yield, and particle growth will not progress, and oxidation of the particle surface will progress during removal, making it difficult to obtain gallium nitride particles with the desired oxygen content. The upper limit is preferably 30 hours or less, and more preferably 20 hours or less. If the treatment is continued for longer than this, the particles will grow too large and will not become particles suitable for use.

[0042] The temperature of the ammonia gas for deposition that deposits the vaporized gallium nitride is 900°C or higher and 1100°C or lower, which is the temperature range in which gallium nitride particles can be deposited, and preferably 1000°C or higher and 1100°C or lower. By introducing ammonia gas for deposition in such a temperature range, the vaporized gallium nitride particles are cooled by the ammonia gas for deposition and precipitate. Furthermore, it becomes possible for the deposited gallium nitride particles to grow to a certain particle size. The amount of ammonia gas in this case is such that the molar ratio of nitrogen in the ammonia gas to gallium present in the container is preferably 1 or higher, more preferably 2 or higher, and particularly preferably 3 or higher, in terms of the flow rate per hour.

[0043] The outermost surface of the particles thus precipitated may be decomposed to precipitate metallic gallium. The precipitation of metallic gallium gives the particle surface a curved surface, making it possible to suppress oxidation from the outermost surface. This results in a color close to gray.

[0044] In addition, in order to remove water generated during the nitriding treatment, it is preferable to maintain the temperature at or below the temperature of the nitriding treatment step for several hours between the nitriding treatment step and the step of introducing the ammonia gas to the nitrided gallium oxide.

[0045] The gallium nitride particles of the present invention have a low oxygen content, and therefore can be made into a sintered body with a low oxygen content. The sintered body can be obtained, for example, by hot-pressing the gallium nitride particles of the present invention at a temperature of 1060°C or higher but lower than 1200°C. The hot-pressing method is a device that advances sintering by applying heat while pressing powder. Uniaxial pressure is applied during heating to assist the diffusion of elements within the workpiece during firing, making this a firing method that can sinter even materials that are difficult to sinter, such as those containing elements with low diffusion coefficients or those processing powders with large particle diameters. Sintering using the hot-pressing method improves density compared to conventional methods, reaching, for example, 3.0 g / cm 3 It is possible to obtain a sintered body having a density as high as or higher than this.

[0046] The sintered body made of gallium nitride particles of the present invention has a low oxygen content, making it possible to use it as a sputtering target with a low oxygen content. The sputtering target can be obtained by bonding (fixing) it to, for example, a flat or cylindrical support with an adhesive such as a solder material. The material of the support is not particularly limited as long as it has high thermal conductivity and strength sufficient to support the molded product. Metals such as Cu, SUS, or Ti are preferred because of their high thermal conductivity and strength. Regarding the shape of the support, a flat support is used for a flat molded product, and a cylindrical support is used for a cylindrical molded product. The adhesive (bonding material) used to bond the molded product to the support is not particularly limited as long as it has sufficient adhesive strength to support the product. Conductive resins, tin-based solders, or indium-based solders can be used. Indium solder is preferred because of its high electrical and thermal conductivity, softness, and ease of deformation.

[0047] A sputtering target made using a sintered body of gallium nitride particles of the present invention has a low oxygen content, and therefore can be made into a gallium nitride thin film with good crystallinity. [Effects of the Invention]

[0048] The gallium nitride particles of the present invention can be used to produce high-purity gallium nitride targets with low oxygen content, allowing for the formation of gallium nitride thin films with good crystallinity.Furthermore, the particles can also be used as raw materials for gallium nitride single crystals produced by ammonothermal methods and other methods. [Brief explanation of the drawings]

[0049] [Figure 1] An example of an apparatus for producing gallium nitride particles of the present invention [Figure 2] An example of an apparatus for producing gallium nitride particles of the present invention [Example]

[0050] The present invention will be specifically described using the following examples, but the present invention is not limited to these examples.

[0051] (Oxygen content measurement of particles) The object was pyrolyzed and the oxygen content was measured by the thermal conductivity method using an oxygen, nitrogen and hydrogen analyzer (manufactured by Leco). Oxygen content (at%) = (oxygen content (wt%) / oxygen atomic weight) / (nitrogen content (wt%) / nitrogen atomic weight) + (gallium content (wt%) / gallium atomic weight) + (oxygen content (wt%) / oxygen atomic weight)) The nitrogen content (wt%) was measured using an oxygen / nitrogen / hydrogen analyzer (manufactured by Leco), and the gallium content (wt%) was calculated assuming that the remainder of the nitrogen content was gallium.

[0052] (50% particle size) The 50% particle size of primary particles was determined using an SEM by first observing at 50x magnification, measuring the presence or absence of particles over 100 μm, as well as their diameter and area, then at 200x magnification, measuring the presence or absence of particles between 10 and 100 μm, as well as their diameter and area, then at 1000x magnification, measuring the presence or absence of particles between 5 and 10 μm, as well as their diameter and area, and finally at 5000x magnification, measuring the presence or absence of particles less than 5 μm, as well as their diameter and area. These measurements were taken on at least three images each, and the combined results were used to determine the overall particle size distribution. Particles in this case were considered to have no visible grain boundaries, and particles with grain boundaries, even if aggregated, were calculated as separate particles. The diameter of the particles at 50% cumulative area ratio was determined as the 50% particle size of the primary particles. (Average particle size) The average particle size was measured using an SEM, first at 50x magnification to check for the presence or absence of particles over 100 μm and their diameter, then at 200x magnification to check for the presence or absence of particles between 10 and 100 μm and their diameter, then at 1000x magnification to check for the presence or absence of particles between 5 and 10 μm and their diameter, and finally at 5000x magnification to check for the presence or absence of particles less than 5 μm and their diameter. These measurements were taken at least three times and combined to obtain the overall particle size distribution. Particles in this case were considered to have no visible grain boundaries, and particles with grain boundaries were calculated as separate particles even if they were aggregated. The arithmetic mean diameter of the particles was taken as the average particle size.

[0053] (ammonia gas / gallium molar ratio) It was calculated from the ratio of the number of moles of gallium in the charged gallium oxide or gallium nitride particles to the number of moles of ammonia gas (volume converted at 25°C) calculated from the flow rate and flow time.

[0054] (amount of ammonia gas (NH3) reacted per hour) The amount of ammonia gas reacted per hour was calculated by dividing the molar ratio of ammonia gas to gallium by the reaction retention time. (Lightly packed bulk density) The loose bulk density of the gallium nitride particles was measured in accordance with JIS Z2504. (Measurement of impurities in particles) Impurities in the particles were analyzed using GDMS (glow discharge mass spectrometry).

[0055] Examples 1 to 3 The apparatus used was the tubular furnace shown in Figure 1. 40 g of gallium oxide powder (5N: needle-shaped) was weighed out and placed in an alumina container, which was then placed in container 2 of tubular furnace 1 shown in Figure 1 and subjected to nitriding treatment. After evacuating the furnace, ammonia gas was filled in, and 1000 mL / min of ammonia gas for nitriding treatment was introduced through pipe 10. The temperature of container 2 was raised at a rate of 10°C / min, ultimately reaching 1050°C and maintained at this temperature for 18 hours (ammonia gas / gallium molar ratio = 103.5). After cooling to below 200°C, ammonia gas was introduced at 1000 mL / min through pipe 10 for precipitation. The temperature was increased at 10°C / min. The ammonia gas was introduced into the nitrided gallium oxide heated to 1150°C, vaporizing the gallium nitride. The temperature in vessel 2 was then increased to 1150°C, and ammonia gas for precipitation, heated to 1000°C, was introduced through pipe 20 at 1000 mL / min. The ammonia gas was then heated to 1000°C and introduced at 1000 mL / min for 1, 6, or 12 hours. (The molar ratio of ammonia gas to gallium at introduction was 5.75 for 1-hour treatment, 34.5 for 6-hour treatment, and 69 for 12-hour treatment.) The gallium nitride particles deposited directly above vessel 2 were recovered, and the yield and physical properties were confirmed. The physical properties of the resulting gallium nitride particles are shown in Tables 2 and 3.

[0056] Example 4 The apparatus used was the tubular furnace shown in Figure 2. 40 g of gallium oxide powder (5N: needle-shaped) was weighed out and placed in an alumina container, which was then placed in part 2 of tubular furnace 1 in Figure 2, where nitriding treatment was carried out. After replacing the inside of the furnace with a vacuum, ammonia gas was filled in, and 1000 mL / min of ammonia gas for nitriding treatment was introduced through pipe 10. The temperature of container 2 was raised at a rate of 10°C / min, finally reaching 1050°C, where it was maintained for 18 hours (ammonia gas / gallium molar ratio = 103.5). After cooling to less than 200°C, ammonia gas was introduced at 500 mL / min through pipe 10 for further precipitation. The temperature was increased at 10°C / min. The ammonia gas was introduced into the nitrided gallium oxide heated to 1150°C to vaporize the gallium nitride. After the temperature in vessel 3 was increased to 1150°C, ammonia gas for precipitation was introduced through pipe 20 and heated to 1000°C. The ammonia gas was then introduced at 1000 mL / min and maintained for 6 hours (ammonia gas / gallium molar ratio at introduction: 34.5 for 6 hours). The precipitated particles in vessel 3 were collected, and the yield and physical properties were confirmed. The physical properties and yield of the resulting gallium nitride particles are shown in Table 2.

[0057] Example 5 The apparatus used was the tubular furnace shown in Figure 1. 40 g of gallium oxide powder (5N: needle-shaped) was weighed out and placed in an alumina container, which was then placed in container 2 of tubular furnace 1 shown in Figure 1 and subjected to nitriding treatment. After the inside of the furnace was evacuated, it was filled with ammonia gas, and 1000 mL / min of ammonia gas for nitriding treatment was introduced through pipe 10. The temperature of container 2 was raised at a rate of 10°C / min, finally reaching 1050°C and maintained at that temperature for 18 hours. Without cooling, ammonia gas was introduced at 1000 mL / min through pipe 10 for further precipitation. The temperature was increased at 10 °C / min. The ammonia gas was introduced into the nitrided gallium oxide heated to 1150 °C, vaporizing the gallium nitride. After vaporizing the gallium nitride, the temperature in vessel 2 was increased to 1150 °C. Ammonia gas for precipitation was then introduced at 1000 mL / min through pipe 20, heated to 1050 °C, and maintained at this temperature for 6 hours (ammonia gas / gallium molar ratio at introduction: 34.5 for 6-hour treatment). The gallium nitride particles precipitated directly above vessel 2 were collected, and the yield and physical properties were confirmed. The physical properties of the resulting gallium nitride particles are shown in Tables 2 and 3.

[0058] Comparative Example 1 Gallium oxide was treated in the same manner as in Examples 1 to 3 using the apparatus shown in Figure 1, except that the temperature during the deposition process when introducing the container and ammonia gas for transport was 1200°C, piping 20 was not used, and ammonia gas was introduced at 1000 ml / min through piping 10. In this case, since ammonia gas for deposition was not used, no gallium nitride particles remained in container 2, and gallium nitride particles were obtained at the outlet of the tubular furnace around the furnace tube. However, because the average particle size was small and they were deposited on the furnace tube, the oxygen content and purity were low, and the desired product was not obtained. The physical properties of the obtained gallium nitride particles are shown in Tables 2 and 3.

[0059] Comparative Example 2 Gallium oxide was treated in the same manner as in Comparative Example 1, except that the temperature during the deposition process when introducing the container and ammonia gas for transportation was 1125°C, piping 20 was not used, ammonia gas was introduced from piping 10 at 1000 ml / min, and heat treatment was carried out for 6 hours. When the physical properties were measured, it was found that there was no vapor deposition, so the average particle size was large and there were many impurities, and the desired properties were not obtained. The physical properties of the obtained gallium nitride particles are shown in Tables 2 and 3.

[0060] Comparative Example 3 Gallium oxide was treated in the same manner as in Examples 1 to 3, except that the precipitation treatment was not performed. Since the precipitation treatment was not performed, gallium nitride particles were obtained, but the average particle size was small, the oxygen content was high, and the purity was low, so the desired particles were not obtained. The physical properties of the obtained gallium nitride particles are shown in Tables 2 and 3.

[0061] [Table 1]

[0062] [Table 2]

[0063] [Table 3] [Explanation of symbols]

[0064] 1 Furnace 2 Gallium oxide filled container 3. Container for collecting precipitated gallium nitride particles 10 Piping 20 Piping

Claims

1. A method for producing gallium nitride particles, characterized in that gallium oxide is used as a starting material for nitriding, and then ammonia gas for transportation heated to a temperature of 1150°C or higher and 1300°C or lower as a precipitation treatment is introduced into the gallium oxide that has been nitrided and heated to a temperature of 1150°C or higher and 1300°C or lower, and the vaporized gallium nitride is precipitated by introducing ammonia gas for precipitation heated to 900°C or higher and 1100°C or lower, wherein the oxygen content is 0.5 at% or less and the total impurity amount of the elements Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd is less than 10 wtppm.

2. The manufacturing method described in claim 1, wherein the purity of the gallium oxide is 4N or more.

3. A manufacturing method described in claim 1 or 2, wherein the nitriding temperature of the nitriding treatment is 1000°C or higher and 1100°C or lower.

4. A manufacturing method described in any one of claims 1 to 3, wherein the treatment time for the nitriding treatment is 3 hours or more.

5. A manufacturing method described in any one of claims 1 to 4, wherein the temperature of the ammonia gas for transportation is 1150°C or higher and 1200°C or lower.

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