Gallium nitride particles and method for producing the same

Abstract

To provide a high-purity gallium nitride particles having a low oxygen content suitable for a raw material or a sintered body.SOLUTION: Gallium nitride particles are characterized in that the oxygen content is 0.5 at.% or less and the total impurity amount of elements, Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn and Cd, is less than 10 wtppm.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 when manufacturing a gallium nitride thin film by a sputtering method.

Background Art

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

[0003] As a method for producing a gallium nitride thin film, a sputtering method using a target can be mentioned. A sputtering target of gallium nitride is produced by molding or sintering gallium nitride powder. However, if the oxygen content of the gallium nitride powder, which is the raw material of the target, is high, a gallium nitride film containing a large amount of oxygen is formed, resulting in a problem of reduced crystallinity. Further, until now, when trying to reduce the amount of oxygen, the particle size becomes large, and particularly when trying to obtain a sintered body exceeding 120 mm, there is a problem that the strength is insufficient and the shape cannot be maintained. In addition, when used in various devices, a high purity is required for the gallium nitride sputtering target as a raw material in order to control the amounts of various dopants, but such sintered bodies have not been able to be produced until now.

[0004] Generally, as a method for producing gallium nitride powder, a method of heating metallic gallium in an ammonia gas stream at 1000°C or higher and 1200°C or lower to obtain polycrystalline gallium nitride is known. In this method, since gallium nitride is formed on the surface of metallic gallium, the gallium nitride inhibits the contact between the internal metallic gallium and ammonia gas, and the nitridation reaction does not proceed further. Further, since the melting point of metallic gallium is as low as about 30°C, it becomes liquid during the nitridation treatment, the reaction surface is small, and the reaction hardly proceeds.

[0005] Another method involves heating gallium oxide in an ammonia gas atmosphere to obtain gallium nitride (see, for example, Patent Documents 1-2). While this method identifies the substance obtained by X-ray fluorescence and electron beam microanalysis (EPMA) as gallium nitride, it does not mention the amount of trace impurities in the powder, nor does it provide detailed information about the ammonia gas atmosphere.

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

[0007] Patent Document 4 discloses a technique for obtaining gallium nitride powder by nitriding Ga2O gas, which is obtained by vaporizing gallium oxide in a reducing atmosphere. However, the gallium source gas contains a large amount of oxygen, making it impossible to obtain powder that is both low in oxygen and high in purity.

[0008] Furthermore, while Patent Document 5 discloses a technology relating to gallium nitride particles with a low oxygen content, high-purity powder cannot be obtained because the particles are not precipitated after vaporization. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2002-29713 [Patent Document 2] Japanese Patent Publication No. 2000-198978 [Patent Document 3] Japanese Patent Publication No. 2013-129568 [Patent Document 4] Japanese Patent Publication No. 2009-234800 [Patent Document 5] WO2018-230663 publication [Overview of the project] [Problems that the invention aims to solve]

[0010] The objective of the present invention is to provide gallium nitride grains with low oxygen content and low impurities, which can be used to produce low-oxygen, high-density, and high-purity gallium nitride sputtering targets and 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 nitriding conditions and found conditions for obtaining gallium nitride particles with high purity and low oxygen content, thus completing the present invention. It came to this point.

[0012] In other words, the embodiments of the present invention that exist in the following [1] to [8] are as follows:

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

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

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

[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 performing a nitriding treatment using gallium oxide as a starting material, transport ammonia gas heated to a temperature of 1150°C to 1300°C is introduced into nitrided gallium oxide heated to 1150°C to 1300°C as a precipitation treatment, and the vaporized gallium nitride is precipitated by introducing ammonia gas heated to 900°C to 1100°C.

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

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

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

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

[0022] The gallium nitride particles of the present invention are characterized in that the oxygen content is 0.5 at% or less, preferably 0.2 at% or less, and more preferably 0.1 at% or less. Thereby, it becomes 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 in that the total amount of impurities of the elements Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, Cd is less than 10 wtppm. The elements listed here are inclusions for making p-type and n-type semiconductors of gallium nitride, and in order to control the inclusions, it is necessary that they are not contained in the gallium nitride particles which are the raw materials. The total amount of impurities is preferably 5 wtppm or less, more preferably 3 wtppm or less, still 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 with a high activation rate is preferably 5 wtppm or less in total, more preferably 2 wtppm or less, still more preferably 1 wtppm, and even more preferably 0.5 ppm or less. Further, the amount of Si impurities is preferably 1 wtppm or less, and more preferably 0.5 ppm or less.

[0025] In the present invention, the gallium nitride particles, which are substantially spherical, preferably have a 50% particle diameter of 5 μm or less for the primary particles, and more preferably 3 μm or less. This allows the substantially spherical gallium nitride particles to fully exhibit their effects in terms of low oxygen and high sinterability.

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

[0027] Furthermore, the gallium nitride particles of the present invention preferably have a 50% particle diameter of 5 μm or more and 50 μm or less of the primary particles, 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 diameter to 5 μm or more, it is possible to reduce the effect of surface oxidation and further reduce the amount of oxygen, and it is also possible to improve the density during sintering. In addition, it is possible to suppress to some extent the decomposition at high temperatures that can normally occur due to the small surface area, and it is also possible to raise the firing temperature. By setting the particle diameter to 50 μm or less, the surface area is large, making it easier to proceed with sintering. The particle diameter here refers to the 50% particle diameter of the area of ​​the primary particles observed with a scanning electron microscope or the like.

[0028] In this invention, the gallium nitride particles with a large particle diameter are preferably plate-shaped. This is because, unlike crystal growth that starts from a conventional substrate, growth starts from the particles themselves, resulting in mainly plate-shaped lateral growth rather than columnar growth along the c-axis. Since the final product is sintered into a plate shape, a plate shape is preferable to a columnar shape.

[0029] The bulk density of the lightly packaged product is 1.2 g / cm³. 3 It is preferable that it be greater than 1.4 g / cm³. 3 Larger, and more preferably 1.6 g / cm³ 3It is larger. This results in higher packing efficiency, easier densification during firing, and a smaller occupied volume when used as a raw material for single crystals, allowing for smaller containers.

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

[0031] The present invention relates to a method for producing gallium nitride particles, in which gallium oxide is used as a starting material and subjected to a nitriding treatment, and then, as a precipitation treatment, transport ammonia gas heated to a temperature of 1150°C to 1300°C is introduced into the nitrided gallium oxide heated to 1150°C to 1300°C, and the vaporized gallium nitride is precipitated by introducing a deposition ammonia gas heated to 900°C to 1100°C to obtain gallium nitride particles.

[0032] In this invention, the purity of the gallium oxide used 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 is possible to obtain gallium nitride particles of high purity.

[0033] The nitriding temperature for gallium oxide during the nitriding treatment is preferably between 1000°C and 1100°C, and more preferably between 1025°C and 1075°C. By treating within this range, it is possible to nitrid the gallium oxide while suppressing vaporization.

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

[0035] During the nitriding treatment, the flow rate of ammonia gas is preferably such that the molar ratio of nitrogen in ammonia gas to gallium in gallium oxide is 5 or more, and more preferably 10 or more, in order to allow the nitriding to proceed without decomposing the gallium. Furthermore, by setting the ammonia gas flow rate during the nitriding treatment within the above range, it is possible to suppress the vaporization reaction of gallium oxide and the decomposition reaction of synthesized gallium nitride.

[0036] After nitriding, a transport ammonia gas heated to a temperature of 1150°C to 1300°C is introduced into the nitrided gallium oxide, which has also been heated to 1150°C to 1300°C, as a further precipitation treatment. The temperature of the transport ammonia gas is preferably 1150°C to 1200°C. By processing within this range, it is possible to obtain highly purified, vaporized gallium nitride particles without decomposing it into nitrogen and gallium. If transport ammonia gas is not used, the gallium nitride will decompose into nitrogen and gallium, making it impossible to obtain the desired product.

[0037] The time for introducing transport ammonia gas into nitrided gallium oxide heated to 1150°C to 1300°C is preferably 3 hours or more, and more preferably 6 hours or more. If the time is less than the above, the amount of precipitate will be small and the yield will be low, and grain growth will not progress, making it difficult to obtain gallium nitride particles with the desired amount of oxygen due to oxidation of the particle surface during extraction. The upper limit is preferably within 30 hours, and more preferably within 20 hours. If the time exceeds the above, the grains will grow too large and will not become particles suitable for the intended use.

[0038] As a deposition process, transport ammonia gas is introduced into nitrided gallium oxide, and then deposition ammonia gas heated to between 900°C and 1100°C is further introduced into the vaporized gallium nitride to precipitate it. Introducing deposition ammonia gas makes it possible to precipitate vaporized gallium nitride particles. The key is to use ammonia gas for deposition. Simply lowering the temperature inside the furnace would result in deposition preferentially occurring on the furnace walls, leading to a high concentration of impurities originating from the furnace material. Furthermore, if a reactive gas such as ammonia gas is not present during deposition, metallic gallium or gallium oxide will precipitate due to nitrogen deficiency. In addition, 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 an extended period, it separates into nitrogen and hydrogen, and the reactive species (such as NH2) necessary for the reaction with gallium cannot be obtained, preventing the deposition reaction from proceeding. At even lower temperatures, the particles become very fine, making it impossible to maintain the oxygen content.

[0039] By setting the ammonia gas temperature for precipitation as described above, it becomes possible to grow the particles without further decomposition. In this way, by vaporizing, precipitating, and growing gallium nitride particles, it is possible to increase the purity of the gallium nitride particles. Furthermore, in order to increase purity, it is preferable that there are no substrates or seed crystals of gallium nitride particles at the precipitation site. If substrates or seed crystals are present, oxygen and impurities caused by them will be introduced, making it difficult to obtain high-purity gallium nitride particles. Also, if grown on a substrate, it will not grow into particulate matter, requiring post-processing such as crushing, which can lead to the introduction of impurities. The particles precipitated in this way have a high bulk density and become a more useful material for the fabrication of sintered bodies and single crystal synthesis.

[0040] The location where the vaporized gallium nitride particles are deposited can be freely set using 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. Shorter treatment times result in insufficient precipitation and low yield, as well as insufficient grain growth. Furthermore, oxidation of the particle surface progresses during extraction, 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. Treatment beyond this time leads to excessive grain growth, resulting in particles unsuitable for the intended application.

[0042] The temperature of the ammonia gas used to precipitate vaporized gallium nitride is in the temperature range where gallium nitride particles can precipitate, which is 900°C to 1100°C, preferably 1000°C to 1100°C. By introducing ammonia gas in such a temperature range, the vaporized gallium nitride particles are cooled by the ammonia gas and precipitate. Furthermore, the precipitated gallium nitride particles can be grown to a certain particle size. The amount of ammonia gas used in this process is preferably such that the molar ratio of nitrogen in the ammonia gas to gallium contained in the container is 1 or more, more preferably 2 or more, and particularly preferably 3 or more.

[0043] The outermost surface of the particles precipitated in this way may decompose, resulting in the deposition of metallic gallium. The deposition of metallic gallium gives the particle surface a curved shape, which can suppress oxidation from the outermost surface. As a result, the color becomes close to gray.

[0044] Furthermore, in order to remove the water generated during the nitriding process, it is preferable to maintain the temperature below that of the nitriding process for several hours between the nitriding process and the process of introducing the ammonia gas into the nitrided gallium oxide.

[0045] The gallium nitride particles of the present invention have a low oxygen content, which allows for the production of sintered bodies with low oxygen content. Sintered bodies can be obtained, for example, by hot-pressing the gallium nitride particles of the present invention at a temperature of 1060°C to less than 1200°C. The hot-press method is a device that promotes sintering by applying heat while pressurizing powder. By applying uniaxial pressure during heating, it assists in the diffusion of elements within the workpiece during firing. Therefore, it is a firing method that can sinter even materials that are difficult to sinter, such as those containing elements with low diffusion coefficients or when processing powders with large particle sizes. By firing using the hot-press method, the density is improved compared to conventional methods, making it possible to obtain sintered bodies with a high density, for example, 3.0 g / cm³ or more.

[0046] The sintered body made of gallium nitride particles of the present invention has a low oxygen content, making it suitable for use as a sputtering target with low oxygen content. The sputtering target can be obtained by fixing (bonding) it to a flat or cylindrical support using an adhesive such as solder. The material of the support is not particularly limited as long as it has high thermal conductivity and sufficient strength to support the molded product, but metals such as Cu, SUS, or Ti are preferred due to their high thermal conductivity and strength. For flat molded products, a flat support is used, and for cylindrical molded products, a cylindrical support is used. The adhesive (bonding material) used to bond the molded product and the support is not particularly limited as long as it has sufficient adhesive strength to provide support, and conductive resins, tin-based solder, or indium-based solder can be used. Indium solder is preferred because it has high conductivity, high thermal conductivity, and is soft and easily deformable.

[0047] The sputtering target made using the sintered body composed of gallium nitride particles of the present invention has a low oxygen content, which allows for the formation of a gallium nitride thin film with good crystallinity. [Effects of the Invention]

[0048] By using the gallium nitride particles of the present invention, high-purity gallium nitride with a low oxygen content can be produced, enabling the formation of gallium nitride thin films with good crystallinity. Furthermore, it can also be used as a raw material for gallium nitride single crystals produced by methods such as amonothermal synthesis. [Brief explanation of the drawing]

[0049] [Figure 1] An example of an apparatus for producing gallium nitride particles according to the present invention. [Figure 2] An example of an apparatus for producing gallium nitride particles according to the present invention. [Examples]

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

[0051] (Measurement of oxygen content in particles) The target material was thermally decomposed, and the oxygen content was measured using the thermal conductivity method with an oxygen, nitrogen, and hydrogen analyzer (manufactured by Leco). Since the calculated value is wt%, the 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, and hydrogen analyzer (Leco), and the gallium content (wt%) was calculated assuming that the remainder after oxygen and nitrogen was gallium.

[0052] (50% particle size) The 50% particle size of the primary particles was determined using a scanning electron microscope (SEM). First, observations were made at 50x magnification to check for the presence of particles larger than 100 μm, as well as their diameter and area. Next, at 200x magnification, the presence of particles between 10 and 100 μm, as well as their diameter and area, were measured. Then, at 1000x magnification, the presence of particles between 5 and 10 μm, as well as their diameter and area, were measured. Finally, at 5000x magnification, the presence of particles smaller than 5 μm, as well as their diameter and area, were measured. At least three measurements were taken for each of these measurements, and the overall particle size distribution was obtained by combining them. In this calculation, particles without visible grain boundaries were considered; even if aggregated, particles with grain boundaries were treated as separate particles. The diameter of the particle at the 50% cumulative area ratio was defined as the 50% particle size of the primary particles. (Average particle size) The average particle size was determined using a scanning electron microscope (SEM). First, observations were made at 50x magnification to check for the presence and diameter of particles larger than 100 μm. Next, at 200x magnification, the presence and diameter of particles between 10 and 100 μm were measured. Then, at 1000x magnification, the presence and diameter of particles between 5 and 10 μm were measured. Finally, at 5000x magnification, the presence and diameter of particles smaller than 5 μm were measured. At least three measurements were taken for each of these measurements, and the overall particle size distribution was obtained by combining them. In this calculation, particles without visible grain boundaries were considered; even if aggregated, particles with grain boundaries were treated as separate particles. The arithmetic mean diameter of these particles was defined as the average particle size.

[0053] (Molar ratio of ammonia gas to gallium) The ratio was calculated from the number of moles of gallium in the gallium oxide or gallium nitride particles introduced, the flow rate, and the number of moles of ammonia gas (volume equivalent at 25°C) calculated from the flow time.

[0054] (Amount of ammonia gas (NH3) reacted per hour) The amount of ammonia gas reacted per hour was calculated by (molar ratio of ammonia gas to gallium) / reaction holding time. (Lightweight bulk density) The bulk density of gallium nitride particles was measured in accordance with JIS Z 2504. (Measurement of impurity content in particles) Impurities in the particles were analyzed using GDMS (glow discharge mass spectrometry).

[0055] Examples 1-3 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 in Figure 1, and nitriding treatment was performed. After purging the furnace with vacuum, ammonia gas was filled in, and 1000 mL / min of ammonia gas for nitriding treatment was introduced through piping 10. The temperature of container 2 was raised at a rate of 10°C / min, and finally raised to 1050°C, where it was maintained for 18 hours (molar ratio of ammonia gas / gallium = 103.5). After cooling to below 200°C, a further precipitation treatment was performed by introducing 1000 mL / min of transport ammonia gas from pipe 10. The temperature was raised at 10°C / min, and the ammonia gas was introduced into the nitrided gallium oxide heated to 1150°C. After vaporizing the gallium nitride, the container 2 was heated to 1150°C, and 1000 mL / min of precipitation ammonia gas, heated to 1000°C, was introduced into the vaporized gallium nitride from pipe 20. This was held for 1 hour, 6 hours, or 12 hours (molar ratio of ammonia gas to gallium at introduction: 1-hour treatment: 5.75, 6-hour treatment: 34.5, 12-hour treatment: 69). The gallium nitride particles precipitated directly above container 2 were collected, and the yield and various physical properties were confirmed. The physical properties of the obtained 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, placed in an alumina container, and then placed in section 2 of tubular furnace 1 in Figure 2 for nitriding treatment. After purging the furnace with vacuum, ammonia gas was filled in, and 1000 mL / min of ammonia gas for nitriding treatment was introduced through piping 10. The temperature of container 2 was raised at a rate of 10°C / min, and finally raised to 1050°C, where it was maintained for 18 hours (molar ratio of ammonia gas / gallium = 103.5). After cooling to below 200°C, a further precipitation treatment was performed by introducing 500 mL / min of transport ammonia gas from pipe 10. The temperature was raised at 10°C / min, and the transport ammonia gas was introduced into the nitrided gallium oxide heated to 1150°C. After vaporizing the gallium nitride, the container 3 was heated to 1150°C, and 1000 mL / min of precipitation ammonia gas, heated to 1000°C, was introduced into the vaporized gallium nitride from pipe 20 at 1000°C. This was held for 6 hours (molar ratio of ammonia gas to gallium at input: 6-hour treatment: 34.5). The precipitated particles in container 3 were collected, and the yield and various physical properties were confirmed. The physical properties and yield of the obtained gallium nitride particles are shown in Table 2.

[0057] Example 5 The apparatus used was the tubular furnace shown in Figure 1. 40g 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 in Figure 1, and nitriding treatment was performed. After purging the furnace with vacuum, ammonia gas was filled in, and 1000 mL / min of ammonia gas for nitriding treatment was introduced through piping 10. The temperature of container 2 was raised at a rate of 10°C / min, and finally raised to 1050°C, where it was maintained for 18 hours. Without cooling, a further precipitation treatment was performed by introducing 1000 mL / min of transport ammonia gas from pipe 10, raising the temperature by 10°C / min, and introducing the ammonia gas into the nitrided gallium oxide heated to 1150°C. After vaporizing the gallium nitride, the container 2 was heated to 1150°C, and 1000 mL / min of ammonia gas for precipitation was introduced from pipe 20, heated to 1050°C, into the vaporized gallium nitride. This was held for 6 hours (molar ratio of ammonia gas to gallium at introduction: 6-hour treatment: 34.5). The gallium nitride particles precipitated directly above container 2 were collected, and the yield and various physical properties were confirmed. The physical properties of the obtained gallium nitride particles are shown in Tables 2 and 3.

[0058] Comparative Example 1 Using the apparatus shown in Figure 1, gallium oxide was treated in the same manner as in Examples 1-3, except that the temperature for introducing the container and transport ammonia gas during the precipitation process was set to 1200°C, and piping 20 was not used, while ammonia gas was introduced from piping 10 at a rate of 1000 ml / min. In this case, since ammonia gas for precipitation was not used, no gallium nitride particles remained in container 2. Gallium nitride particles that had precipitated around the core tube were obtained at the outlet of the tubular furnace, but the average particle size was small, and because they had precipitated on the core tube, the oxygen content and purity were low, and the desired result could not be obtained. The physical properties of the obtained gallium nitride particles are shown in Tables 2 and 3.

[0059] Comparative Example 2 The gallium oxide was treated in the same manner as in Comparative Example 1, except that the temperature for introducing the ammonia gas into the container and transport during the precipitation treatment was set to 1125°C, and instead of using pipe 20, ammonia gas was introduced from pipe 10 at a rate of 1000 ml / min for 6 hours of heat treatment. When its physical properties were measured, vapor deposition did not occur, resulting in a large average particle size and a high amount of impurities, which did not meet the specified requirements. 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 1-3, except that the precipitation treatment was omitted. Because the precipitation treatment was omitted, gallium nitride particles were obtained, but they had a small average particle size, a high oxygen content, and low purity, and the desired material could not be 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. Gallium nitride particles characterized by having an oxygen content of 0.5 at% or less, a total impurity amount of the elements Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd of less than 10 wt ppm, a total impurity amount of Mg and Si of less than 5 wt ppm, and an average particle diameter of 4 μm or more and 20 μm or less.

2. Gallium nitride particles according to claim 1, characterized in that the total amount of Mg and Si impurities is less than 2 wt ppm.

3. Gallium nitride particles according to claim 1 or 2, characterized in that the amount of Si impurities is less than 1 wt ppm.

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

5. A sintered body comprising gallium nitride particles according to any one of claims 1 to 4.

6. A sputtering target comprising the sintered body described in claim 5.

7. A method for producing a gallium nitride thin film, comprising using the sputtering target described in claim 6.

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