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 in producing a gallium nitride thin film by a sputtering method. [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 the sputtering method using a target. Gallium nitride sputtering targets are produced by molding or sintering gallium nitride powder, but if the oxygen content of the gallium nitride powder, which is the raw material for the target, is high, the gallium nitride film will contain a lot of oxygen, which causes a problem of reduced crystallinity. In addition, in the past, attempts to reduce the amount of oxygen resulted in larger particle sizes, and there was a problem that sintered bodies exceeding 120 mm in size were unable to maintain their shape due to insufficient strength. In addition, when using gallium nitride sputtering targets as raw materials in order to control the amount of various dopants, high purity is required for the raw material, but such sintered bodies have not been able to be produced until now.

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

[0005] Another method is to obtain gallium nitride by heating gallium oxide in an ammonia gas atmosphere (see, for example, Patent Documents 1 and 2). In this method, the obtained substance is identified as gallium nitride using fluorescent X-rays or an electron probe microanalyzer (EPMA), but there is no description of the amount of trace impurities in the powder, nor 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 having an oxygen content below a certain level.

[0007] Patent Document 4 describes a method for producing a gallium oxide film by vaporizing gallium oxide in a reducing atmosphere. 2 A technology has been disclosed for obtaining gallium nitride powder by nitriding O gas, but the gallium source gas contains a large amount of oxygen, making it impossible to obtain powder that has both low oxygen content and high purity.

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

[0009] [Patent Document 1] JP 2002-29713 A [Patent Document 2] JP 2000-198978 A [Patent Document 3] JP 2013-129568 A [Patent Document 4] JP 2009-234800 A [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 grains with a low oxygen content and low impurities that can be used to produce gallium nitride single crystals. [Means for solving the problem]

[0011] In view of this background, the present inventors have conducted extensive research and have investigated nitridation conditions, and have found conditions for obtaining gallium nitride particles with high purity and low oxygen content, thereby completing the present invention. This is what I came to do.

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

[0013] (1) Gallium nitride particles having 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 Mg and Si impurities is less than 5 wtppm.

[0015] (3) Gallium nitride particles according to (1) or (2), characterized in that the total impurity content 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 treatment is performed using gallium oxide as a starting material, ammonia gas for transportation heated to a temperature of 1150°C or more and 1300°C or less as a precipitation treatment is introduced into the gallium oxide that has been subjected to the nitriding treatment heated to a temperature of 1150°C or more and 1300°C or less, 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 comprising gallium nitride particles according to any one of (1) to (4).

[0019] (7) A sputtering target comprising 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 having 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 in that the total impurity amount of the elements Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd is less than 10wtppm. These elements are contained to make gallium nitride a p-type or n-type semiconductor, and in order to control the contents, it is necessary that they are not contained in the gallium nitride particles, which are the raw material. The total impurity amount is preferably 5wtppm or less, more preferably 3wtppm or less, more preferably 1ppm or less, and even more preferably 0.5ppm or less.

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

[0025] In the gallium nitride particles of the present invention, the 50% particle size of the primary particles of the substantially spherical gallium nitride particles is preferably 5 μm or less, and more preferably 3 μm or less, which allows the substantially spherical gallium nitride particles to fully exhibit the effects of low oxygen and high sinterability.

[0026] The average particle size of the gallium nitride particles of the present invention is preferably 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. This makes the particles suitable for densification during firing.

[0027] In addition, the gallium nitride particles of the present invention preferably have a 50% particle size 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 making the particle size 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. In addition, since the surface layer is small, it is possible to suppress decomposition at high temperatures that usually occurs to some extent, and it is also possible to increase the sintering temperature. By making the particle size 50 μm or less, the surface is large, making it easy to proceed with sintering. The particle size here refers to the 50% particle size in the area of ​​the primary particles observed with a scanning electron microscope or the like.

[0028] The shape of the gallium nitride of the present invention is preferably plate-shaped for large grains. This is because, unlike normal crystal growth that starts from a substrate, the grains grow as starting points, so plate-shaped lateral growth occurs primarily, rather than columnar growth along the c-axis. Since the material is ultimately sintered into a plate shape, a plate shape is more preferable than a columnar shape.

[0029] The light bulk density is 1.2g / cm 3 Preferably, it is greater than 1.4 g / cm 3 More preferably 1.6 g / cm 3This allows for high packing properties, makes it easier to densify during firing, and reduces the volume occupied by the container when used as a raw material for single crystals, making it possible to downsize the container.

[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 performing a nitriding process on gallium oxide as a starting material, introducing ammonia gas for transportation heated to a temperature of 1150°C or more and 1300°C or less as a precipitation process into the gallium oxide that has been subjected to the nitriding process heated to a temperature of 1150°C or more and 1300°C or less, and precipitating the vaporized gallium nitride by introducing ammonia gas for precipitation heated to a temperature of 900°C or more and 1100°C or less.

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

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

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

[0035] The flow rate of ammonia gas during the nitriding process is preferably such that the molar ratio of nitrogen in ammonia gas / gallium in gallium oxide is 5 or more, more preferably 10 or more, in order to allow the nitriding process to proceed without decomposing into gallium. Furthermore, the ammonia gas reaction amount per hour is preferably 1 molar or more relative to the amount of gallium input, more preferably 1.5 molar or more, and particularly preferably 2 molar or more. By setting the ammonia gas flow rate during the nitriding process 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 the nitriding process, ammonia gas for transportation heated to a temperature of 1150°C to 1300°C is introduced into the gallium oxide that has been subjected to the nitriding process and heated to a temperature of 1150°C to 1300°C as a further precipitation process. The temperature of the ammonia gas for transportation is preferably 1150°C to 1200°C. By processing within this range, it is 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 cannot be obtained.

[0037] The time for introducing the ammonia gas for transportation into the gallium oxide that has been subjected to the nitriding treatment and heated to 1150°C or more and 1300°C or less is preferably 3 hours or more, more preferably 6 hours or more. If the time is less than the above, the amount of precipitation is small and the yield is low, and the grain growth does not proceed, and the oxidation of the particle surface proceeds during removal, making it difficult to obtain gallium nitride particles with a predetermined oxygen content. The upper limit is preferably within 30 hours, more preferably within 20 hours. If the time exceeds the above, the grains grow too large and become particles that are not suitable for use.

[0038] As a deposition process, ammonia gas for transportation is introduced into the gallium oxide that has been subjected to the nitriding process, and then ammonia gas for deposition, which has been heated to 900°C to 1100°C, is further introduced into the vaporized gallium nitride to cause deposition. By introducing ammonia gas for deposition, vaporized gallium nitride particles can be precipitated. The important thing is to use ammonia gas for deposition. If the temperature inside the furnace is simply lowered, deposition will occur preferentially on the furnace wall, resulting in the deposition of a large amount of impurities caused by the furnace material. Furthermore, if no reactive gas such as ammonia gas is present during deposition, metallic gallium or gallium oxide will deposit due to a lack of nitrogen. Furthermore, the ammonia gas used for deposition must be sprayed on the deposition area within 30 seconds after the specified temperature is reached. If ammonia gas is exposed to temperatures of 1000°C or higher for a long period of time, it will separate into nitrogen and hydrogen, and the active species (NH 2 etc.) is not obtained, and the precipitation reaction does not proceed. Furthermore, at low temperatures, the particles become fine and the amount of oxygen cannot be maintained.

[0039] By setting the temperature of the ammonia gas for precipitation as described above, it becomes possible to grow the particles without decomposing again. In this way, the purity of the gallium nitride particles can be increased by precipitation and particle growth after vaporization of the gallium nitride particles. Furthermore, in order to increase the purity, it is preferable that there is no substrate or seed crystal of the gallium nitride particles at the precipitation site. If a substrate or seed crystal is present, oxygen or impurities caused by them will be mixed in, making it difficult to obtain high-purity gallium nitride particles. In addition, when grown on a substrate, it does not grow in a granular form, so a post-process such as crushing is required, which causes impurities to be mixed in. The particles precipitated in this way have a large light bulk density, making them more useful as a material for producing sintered bodies and synthesizing single crystals.

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

[0041] The time for the precipitation treatment is preferably 3 hours or more, more preferably 6 hours or more. If the time is shorter than that, the amount of precipitation is small and the yield is low, and the grain growth does not proceed, and oxidation of the grain surface proceeds during removal, making it difficult to obtain gallium nitride grains with a predetermined amount of oxygen. The upper limit is preferably within 30 hours, more preferably within 20 hours. If the treatment is continued for longer than that, the grains grow too large to become grains suitable for use.

[0042] The temperature of the ammonia gas for precipitation, which precipitates the vaporized gallium nitride, is 900°C or more and 1100°C or less, which is a temperature range in which gallium nitride particles can be precipitated, and is preferably 1000°C or more and 1100°C or less. By introducing the ammonia gas for precipitation in such a temperature range, the vaporized gallium nitride particles are cooled by the ammonia gas for precipitation and precipitated. Furthermore, it becomes possible to grow the precipitated gallium nitride particles to a certain particle size. The amount of ammonia gas at this time is preferably such that the molar ratio of nitrogen in the ammonia gas / gallium present in the container is 1 or more, more preferably 2 or more, and particularly preferably 3 or more, as a 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 order to remove water generated during the nitriding process, it is preferable to maintain the temperature at or below the temperature of the nitriding process for several hours between the nitriding process and the process of introducing the ammonia gas into the nitriding-treated 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 and lower than 1200°C. The hot pressing method is a device that advances sintering by applying heat while pressing the powder, and since uniaxial pressing during heating assists the diffusion of elements in the workpiece during firing, it is a firing method that can sinter even materials that are difficult to sinter, such as when they contain elements with a low diffusion coefficient or when processing powder with a large particle size. By firing using the hot pressing method, the density is improved compared to conventional methods, and it is possible to obtain a sintered body with a high density of, for example, 3.0 g / cm3 or higher.

[0046] The sintered body made of gallium nitride particles of the present invention has a low oxygen content, and therefore can be used as a sputtering target with a low oxygen content. The sputtering target can be obtained by, for example, fixing (bonding) 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 to support the molded product, and metals such as Cu, SUS, or Ti are preferred because of their high thermal conductivity and high strength. The shape of the support is such that 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) that bonds the molded product to the support is not particularly limited as long as it has sufficient adhesive strength to support the product, and conductive resin, tin-based solder material, or indium-based solder material can be used. Indium solder is preferred because it has high electrical conductivity and thermal conductivity, is soft, and is easily deformed.

[0047] A sputtering target formed using a sintered body of gallium nitride particles of the present invention has a low oxygen content and can therefore form a gallium nitride thin film with good crystallinity. Effect of the Invention

[0048] By using the gallium nitride particles of the present invention, it is possible to produce a high-purity gallium nitride get with a low oxygen content, and form a gallium nitride thin film with good crystallinity. Furthermore, it can be used as a raw material for gallium nitride single crystals produced by the ammonothermal method or the like. [Brief description of the drawings]

[0049] [Figure 1] An example of an apparatus for producing the gallium nitride particles of the present invention [Diagram 2] An example of an apparatus for producing the gallium nitride particles of 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] (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). Since the calculation is in wt%, 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 amount of nitrogen (wt%) was measured using an oxygen / nitrogen / hydrogen analyzer (manufactured by Leco), and the amount of gallium (wt%) was calculated assuming oxygen and the remainder of nitrogen as gallium.

[0052] (50% particle size) The 50% particle size of the primary particles was measured by first observing at 50x magnification using an SEM, measuring the presence or absence of particles over 100μm, as well as their diameter and area, then measuring the presence or absence of particles between 10 and 100μm, as well as their diameter and area, then measuring the presence or absence of particles between 5 and 10μm, as well as their diameter and area, at 1000x magnification, measuring the presence or absence of particles between 5 and 10μm, as well as their diameter and area, and finally measuring the presence or absence of particles less than 5μm, as well as their diameter and area, at 5000x magnification, and these measurements were taken at least three times and combined to obtain the overall particle size distribution. The particles here were considered to be particles with no grain boundaries observed, and if the grain boundaries existed even if the particles were aggregated, they were calculated as separate particles. The diameter of the particles at the 50% cumulative value of the 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 determine the presence or absence of particles over 100μm and their diameter, then at 200x magnification, to determine the presence or absence of particles between 10 and 100μm and their diameter, then at 1000x magnification, to determine the presence or absence of particles between 5 and 10μm and their diameter, and finally at 5000x magnification, to determine the presence or absence of particles less than 5μm and their diameter, and these measurements were taken at least three times and combined to obtain the overall particle size distribution. The particles in this case were considered to have no grain boundaries, and if there were grain boundaries even when the particles were aggregated, they were calculated as separate particles. The arithmetic average 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 (converted into a volume at 25° C.) calculated from the flow rate and flow time.

[0054] (ammonia gas (NH 3 ) reaction volume) The amount of ammonia gas reacted per hour was calculated by (ammonia gas / gallium molar ratio) / reaction retention time. (Lightweight bulk density) The loose bulk density of the gallium nitride particles was measured in accordance with JIS Z2504. (Measuring the amount 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 the container 2 of the 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 from the pipe 10. The temperature of the container 2 was raised at 10°C / min, and finally raised to 1050°C and held for 18 hours (molar ratio of ammonia gas / gallium = 103.5). After the temperature was lowered to less than 200°C, 1000mL / min of ammonia gas for transportation was introduced from the pipe 10 as a precipitation treatment, the temperature was raised at 10°C / min, and the ammonia gas for introduction was introduced into the gallium oxide that had been subjected to the nitriding treatment heated to 1150°C, and the gallium nitride was vaporized. After that, the container 2 part was heated to 1150°C for the vaporized gallium nitride, and the ammonia gas for precipitation was heated to 1000°C and introduced at 1000ml / min from the pipe 20 as the ammonia gas for precipitation, and the temperature was maintained for 1 hour, 6 hours, or 12 hours (molar ratio of ammonia gas / gallium at the time of introduction: 1 hour treatment: 5.75, 6 hour treatment: 34.5, 12 hour treatment: 69). The gallium nitride particles that precipitated directly above the container 2 were collected, and the yield and each physical property were confirmed. The physical properties of the obtained gallium nitride particles are shown in Tables 2 and 3.

[0056] Example 4 The equipment 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 the tubular furnace 1 in Figure 2, where nitriding was performed. After the inside of the furnace was evacuated, it was filled with ammonia gas, and 1000 mL / min of ammonia gas for nitriding was introduced from pipe 10. The temperature of container 2 was raised at 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 lowering the temperature to less than 200°C once, 500mL / min of ammonia gas for transportation was introduced from the pipe 10 as a precipitation treatment, the temperature was raised at 10°C / min, and the ammonia gas for transportation was introduced into the gallium oxide that had been subjected to the nitriding treatment heated to 1150°C to vaporize the gallium nitride. After that, the container 3 was heated to 1150°C for the vaporized gallium nitride, and the ammonia gas for deposition was heated to 1000°C from the pipe 20, and then introduced at 1000ml / min and held for 6 hours (molar ratio of ammonia gas / gallium at the time of introduction: 6-hour treatment: 34.5). The particles precipitated in the container 3 were collected, and the yield and each physical property 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. 40 g of gallium oxide powder (5N: needle-shaped) was weighed out and placed in an alumina container, which was then placed in the container 2 of the 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 from the pipe 10. The temperature of the container 2 was raised at 10°C / min, and finally raised to 1050°C and held for 18 hours. Without lowering the temperature, 1000mL / min of ammonia gas for transportation was introduced from the pipe 10 as a precipitation treatment, the temperature was raised at 10°C / min, the ammonia gas for introduction was introduced into the gallium oxide that had been subjected to the nitriding treatment heated to 1150°C, and the gallium nitride was vaporized. After that, the container 2 part was heated to 1150°C for the vaporized gallium nitride, and the ammonia gas for precipitation was heated to 1050°C and introduced at 1000ml / min from the pipe 20 as the ammonia gas for precipitation, and held for 6 hours (molar ratio of ammonia gas / gallium at the time of introduction: 6-hour treatment: 34.5). The gallium nitride particles precipitated directly above the container 2 were collected, and the yield and each physical property were confirmed. The physical properties of the obtained 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 of Fig. 1, except that the temperature when introducing the container and ammonia gas for transport in the precipitation treatment was 1200°C, piping 20 was not used, and ammonia gas was introduced at 1000ml / min from piping 10. In this case, since ammonia gas for precipitation was not used, no gallium nitride particles remained in the container 2, and gallium nitride particles precipitated around the furnace tube were obtained at the outlet of the tubular furnace. However, since the average particle diameter was small and precipitated on the furnace tube, the oxygen amount and purity were low, and the desired one 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 for introducing the container and ammonia gas for transportation in the precipitation treatment was 1125°C, piping 20 was not used, ammonia gas was introduced from piping 10 at 1000ml / min, and heat treatment was performed for 6 hours. When the physical properties were measured, the average particle size was large and there were many impurities, so the desired properties were not obtained because vaporization and precipitation did not occur. 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 no precipitation treatment was performed. Since no precipitation treatment was performed, gallium nitride particles were obtained, but the average particle size was small, the oxygen content was high, and the purity was low, and 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. 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 wtppm, a total impurity amount of Mg and Si of less than 5 wtppm, and an average particle diameter of 4 μm or more and 20 μm or less.

2. 2. The gallium nitride particle according to claim 1, wherein the total amount of Mg and Si impurities is less than 2 wtppm.

3. 3. The gallium nitride particle according to claim 1, wherein the amount of Si impurity is less than 1 wtppm.

4. 4. The gallium nitride particle according to claim 1, wherein the oxygen content is 0.1 at % or less.

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

6. A sputtering target comprising the sintered body according to claim 5.

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

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