Gallium nitride particles and method for producing same

Abstract

Provided are gallium nitride particles that have a low oxygen content and a high moldability and allow a gallium nitride sputtering target having a high density and a high strength to be produced. By causing a mixed powder of gallium oxide and gallium nitride to react at a temperature of 1000-1100 C. such that an ammonia reaction amount per hour is 1 or more times (by mole) an amount of gallium charged, gallium nitride particles are obtained of which an oxygen content is 1 atm % or less, an average particle size of primary particles is 5 m or more, and a particle size of a range of 10 area % from smallest particles of a particle size distribution (10% particle size) is 3 m or less.

Claims

1. A composition, comprising: a plurality of gallium nitride particles including primary particles, wherein an oxygen content is 1 atm % or less, an average particle size of the primary particles is at least 5 m, the primary particles include substantially spherical particles, and a particle size of a range of 10 area % from smallest particles of a particle size distribution is 3 m or less, and wherein gallium nitride particles that have substantially spherical shapes are from 25 area % to 43.9 area % of all the gallium nitride particles.

2. The composition according to claim 1, wherein a particle size distribution of secondary particles has multiple peaks, an apex of a peak on a side of smallest particle sizes is 90 82 m or less, and a content rate thereof is at least 10 wt % of all the gallium nitride particles.

3. A sintered body, comprising: the composition of claim 2.

4. A sintered body, comprising: the composition of claim 1.

5. A sputtering target, comprising: the sintered body of claim 4.

6. A method for producing a composition, the method comprising: performing a nitriding process that reacts a mixed powder of gallium oxide and gallium nitride at a temperature of from 1000 C. to 1100 C. for at least 3 hours such that an ammonia reaction amount per hour is 1 or more times an amount by mole of gallium charged, wherein the composition comprises a plurality of gallium nitride particles including primary particles, wherein an oxygen content is 1 atm % or less, an average particle size of the primary particles is at least 5 m, the primary particles include substantially spherical particles, and a particle size of a range of 10 area % from smallest particles of a particle size distribution is 3 m or less, and wherein gallium nitride particles that have substantially spherical shapes are from 25 area % to 43.9 area % of all the gallium nitride particles.

7. The method according to claim 6, further comprising: performing a particle growth process that causes a reaction at a temperature of from 1050 C. to 1200 C. for at least 3 hours such that an ammonia reaction amount per hour is 2 or more times an amount by mole of gallium charged, and that a final ammonia/gallium molar ratio is from 50 to less than 1000, wherein the particle growth process is performed after the nitriding process at a temperature higher than the temperature of the nitriding process.

8. The method according to claim 7, wherein the nitriding process is performed at the temperature of from 1025 C. to 1075 C., and the particle growth process is performed at the temperature of from at 1100 C. to 1150 C.

9. A method for producing a composition, the method comprising: performing a nitriding process that reacts a mixed powder of gallium oxide and gallium nitride at a temperature of from 1000 C. to 1100 C. for at least 3 hours such that an ammonia reaction amount per hour is 1 or more times an amount by mole of gallium charged, wherein the composition comprises a plurality of gallium nitride particles including primary particles, wherein an oxygen content is 1 atm % or less, an average particle size of the primary particles is at least 5 82 m, the primary particles include substantially spherical particles, and a particle size of a range of 10 area % from smallest particles of a particle size distribution is 3 m or less, wherein gallium nitride particles that have substantially spherical shapes are from 25 area % to 43.9 area % of all the gallium nitride particles, and wherein a particle size distribution of secondary particles has multiple peaks, an apex of a peak on a side of smallest particle sizes is 90 m or less, and a content rate thereof is at least 10 wt % of all the gallium nitride particles.

10. The method according to claim 9, further comprising: performing a particle growth process that causes a reaction at a temperature of from 1050 C. to 1200 C. for at least 3 hours such that an ammonia reaction amount per hour is 2 or more times an amount by mole of gallium charged, and that a final ammonia/gallium molar ratio is from 50 to less than 1,000, wherein the particle growth process is performed after the nitriding process at a temperature higher than the temperature of the nitriding process.

11. The method according to claim 10, wherein the nitriding process is performed at the temperature of from 1025 C. to 1075 C., and the particle growth process is performed at the temperature of from 1100 C. to 1150 C.

12. The method according to claim 11, wherein the nitriding process is performed for at least 6 hours, and the particle growth process is performed for at least 6 hours.

13. The method according to claim 11, wherein the nitriding process is performed for at least 6 hours, and the particle growth process is performed for at least 12 hours.

Description

EXAMPLES

(1) The present invention is specifically described using the following examples. However, the present invention is not limited to these examples.

(2) (Measurement of Oxygen Content of Particles)

(3) An object was thermal decomposed, and an oxygen content thereof was measured using a thermal conductivity method using an oxygen/nitrogen/hydrogen analyzer (manufactured by Leco Corporation). Since quantities in calculation are in wt %, oxygen content (atm %)=(oxygen content (wt %)/oxygen atomic weight)/((nitrogen content (wt %)/nitrogen atomic content)+(gallium content (wt %)/gallium atomic content)+(oxygen content (wt %)/oxygen atomic weight)), the nitrogen content (wt %) was measured using an oxygen/nitrogen/hydrogen analyzer (manufactured by Leco Corporation), and the gallium content (wt %) was calculated using a remainder of oxygen and nitrogen as gallium.

(4) (Light Bulk Density)

(5) A light bulk density of the gallium nitride particles was measured according to JISZ2504.

(6) (Shapes [Gallium Oxide, and Gallium Nitride])

(7) Shapes of the powered and the particles were observed using an SEM (scanning electron microscope), and the shapes were observed.

(8) (Particle Sizes [Primary Particle Sizes])

(9) For the primary particle sizes, first, observation was performed using an SEM at a 50magnification, and presence or absence of particles of sizes larger than 100 m and diameters and areas thereof were measured. Next, presence or absence of particles of sizes in a range of 10-100 m and diameters and areas thereof were measured at a 200 magnification. Next, presence or absence of particles of sizes in a range of 5-10 m and diameters and areas thereof were measured at a 1000 magnification. Finally, presence or absence of particles of sizes less than 5 m and diameters and areas thereof were measured at a 5000 magnification. These measurements were each performed using at least three samples, and by combining the results, an overall particle size distribution was obtained. The particles here were those in each of which a grain boundary was not observed. Even when particles were agglomerated, when there were grain boundaries, the particles were treated as separate particles in the calculation.

(10) (Particle Sizes [Secondary Particle Sizes])

(11) Regarding secondary particle sizes, the following sieves were stacked in multiple stages. About 5g of particles was added from top. Shaking was performed for 10 minutes. After confirming that there were steady presence of particles at each stage, amounts of particles on the respective sieves were measured, and a particle size distribution was obtained.

(12) Sieve openings used: 1000 m, 355 m, 250 m, 150 m, 106 m, 90 m, 75 m, 53 m, 32 m, 25 m, and a sieve tray.

(13) Particle sizes of particles remaining the sieves are as follows.

(14) 355 m sieve . . . 678 m, 250 m sieve . . . 303 m, 150 m sieve . . . 200 m, 106 m sieve . . . 128 m, 90 m sieve . . . 98 m, 75 m sieve . . . 83 m, 53 m sieve . . . 64 m, 32 m sieve . . . 43 m, 25 m sieve . . . 29 m, sieve tray . . . 13 m

(15) (Ammonia/Gallium Molar Ratio)

(16) It was calculated from a ratio of the number of moles of ammonia calculated from a flow rate and a circulation time period to the number of moles of gallium in the gallium oxide or gallium nitride charged.

(17) (Ammonia (NH.sub.3) Reaction Amount Per Hour)

(18) An ammonia reaction amount per hour was calculated from (ammonia/gallium molar ratio)/(reaction holding time).

(19) (Yield)

(20) A yield was calculated based on an amount obtained with respect to a gallium nitride amount estimated from an amount of the gallium oxide and gallium nitride charged.

Examples 1-2

(21) 28 g of a gallium oxide powder (4N: needle-like shapes) having physical properties shown in Table 1 was weighted and charged into an alumina container. After a filling depth at the time was measured, it was put into an atmosphere control furnace and a nitriding treatment was performed. After inside of the furnace was replaced with vacuum, ammonia was filled in at a rate of 1000 mL/min, and temperature was increased at a rate of 10 C./min and was finally raised to 1050 C. and was held for 6.5 hours (ammonia/gallium molar ratio=53.1). After the temperature was once lowered to below 200 C., further, as a particle growth treatment, ammonia was filled in at a rate of 1000 mL/min, and the temperature was raised at a rate of 10 C./min and was finally raised to 1125 C. and was held for 6 or 12 hours (a molar ratio of (ammonia)/(gallium at the time of charging) was 49 for the 6-hour treatment and 98 for the 12-hour treatment). Particles were collected, and a yield and physical properties were confirmed. The physical property values and yield of the obtained gallium nitride are shown in Table 3.

Example 3

(22) On top of 14 g of gallium oxide powder having physical properties shown in Table 1, 14 g of gallium nitride powder having physical properties shown in Table 1 was sequentially filled. After a filling depth at the time was measured, a nitriding treatment and a particle growth treatment were performed in the same manner as in Example 2. Particles were collected, and a yield and physical properties were confirmed. The physical property values and yield of the obtained gallium nitride are shown in Table 3.

Example 4

(23) A nitriding treatment as shown in Table 1 was performed in the same manner as in Example 2. After that, 14 g of the obtained gallium nitride was weighed and filled, and then, 14 g of gallium nitride having physical properties listed in Table 2 was further filled in a form of lamination, and, as a particle growth treatment, ammonia was filled in at a rate of 1000 mL/min, and the temperature was raised at a rate of 10 C./min and was finally raised to 1125 C. and was held for 12 hours. Particles were collected, and a yield and physical properties were confirmed. The physical property values and yield of the obtained gallium nitride are shown in Table 3.

Example 5

(24) A nitriding treatment and a particle growth treatment were performed in the same manner as in Example 2 except that, instead of the gallium oxide powder, a spherical gallium oxide powder (4N) was used. The physical property values and yield of the obtained gallium nitride are shown in Table 3.

Example 6

(25) Treatments were performed in the same manner as in Example 4 except that the temperature during the particle growth treatment was set to 1100 C.

Comparative Example 1

(26) Gallium oxide was treated in the same manner as in Example 1 except that a particle growth treatment was not performed. In this case, a desired result was not obtained. The physical property values and yield of the obtained gallium nitride are shown in Table 3.

Comparative Example 2

(27) A nitriding treatment and a particle growth treatment were performed in the same manner as in Example 2 except that, instead of the gallium oxide powder, gallium oxide (4N: spherical shapes) having a light bulk density of 2.2 g/cc was used. The physical properties and yield of the obtained gallium nitride are as shown in Table 3, and gallium nitride particles having the desired physical properties were not obtained.

(28) TABLE-US-00001 TABLE 1 Nitriding Process Gallium Nitride Gallium Oxide Primary NH3 Reaction Temperature Light bulk Filling particle Filling Filling reaction Reaction time rising time density amount size amount depth NH3/gallium amount temperature period period Example Shape g/cc g m g mm molar ratio per hour C. hr C./min Example 1 Needle-like 0.46 28 30 53.1 8.2 1050 6.5 10 shape Example 2 Needle-like 0.46 28 30 53.1 8.2 1050 6.5 10 shape Example 3 Needle-like 0.46 14 2.1 14 25 50.1 7.7 1050 6.5 10 shape Example 4 Needle-like 0.46 84 30 17.7 2.7 1050 6.5 10 shape Example 5 Spherical shape 0.76 28 22 53.1 8.2 1050 6.5 10 Example 6 Needle-like 0.46 14 2.1 14 25 50.1 7.7 1050 6.5 10 shape Comparative Needle-like 0.46 84 30 17.7 2.7 1050 6.5 10 Example 1 shape Comparative Spherical shape 2.2 28 8 53.1 8.2 1050 6.5 10 Example 2

(29) TABLE-US-00002 TABLE 2 Particle Growth Process Reactant Gallium Nitride Reaction Temperature Filling Primary Filling NH3 reaction Reaction time rising time Total reaction amount particle Filling depth NH3/gallium amount per temperature period period NH3/gallium g size amount mm molar ratio hour C. hr C./min molar ratio Example 1 49 8.2 1125 6 10 102.1 Example 2 98 8.2 1125 12 10 151.1 Example 3 92.4 7.7 1125 12 10 142.5 Example 4 14 2.1 14 21 92.4 7.7 1125 12 10 110.1 Example 5 98 8.2 1125 12 10 151.1 Example 6 92.4 7.7 1100 12 10 142.5 Comparative 17.7 Example 1 Comparative 98 8.2 1125 12 10 151.1 Example 2

(30) TABLE-US-00003 TABLE 3 Substantially Primary particles Secondary particles spherical particles Average 10% First peak Second peak Average Oxygen content particle particle particle particle Particle particle Yield Ieco size size size size amount size % atm % wt % m m m m % m Example 1 93 0.28 0.11 9.2 1.6 43 128 43.9 3.9 Example 2 92 0.24 0.09 14 2.1 43 128 31 3.1 Example 3 98 0.18 0.07 16 2.7 64 128 26 3.5 Example 4 96 0.2 0.077 14.8 2.5 64 128 28 3.2 Example 5 98 0.21 0.08 14 2.4 43 128 31 3.1 Example 6 92 0.26 0.1 12 1.8 43 128 38 3.2 Comparative 96 2.2 0.84 <0.1 <0.1 43 Example 1 Comparative 98 6.8 2.7 <0.1 <0.1 678 Example 2

(31) The present invention has been described in detail with reference to specific embodiments. However, it is apparent to a person skilled in the art that various changes and modifications can be made without departing from the nature and scope of the present invention.

(32) The entire contents of the specification, tables, claims, drawings and abstract of Japanese Patent Application No. 2017-117465 filed on Jun. 15, 2017 are cited here, and are incorporated as disclosure of the specification of the present invention.