JP7240214B2 - Nitride pulverization method - Google Patents

Description

The present invention relates to a method for pulverizing nitrides.

Nitride powders of elements belonging to Group 5, Group 13, or Group 14 of the periodic table, such as tantalum nitride, aluminum nitride, gallium nitride, and silicon nitride, are used as semiconductor raw materials, and are of high purity and are not contaminated with impurities. are sought. Nitride powder is usually produced by pulverizing nitride bulk, but when physical energy or thermal energy is applied, it reacts with a small amount of oxygen in the atmosphere and is oxidized, increasing the amount of oxygen in the nitride. put away. In fact, it has been reported that the amount of oxygen in the nitride increased when bulk silicon nitride or aluminum nitride was pulverized (Non-Patent Documents 1 and 2).

Conventionally, as a method for pulverizing aluminum nitride in which contamination by impurities and oxygen is suppressed as much as possible, a method of pulverizing aluminum nitride using a pot made of an organic polymer and zirconia balls has been proposed (Patent Document 1).

JP-A-61-275111

The Chemical Society of Japan, 2 (1989) J. Soc. Mat. Sci., Japan, 54, 6 (2005)

However, it is difficult to completely block out the inclusion of oxygen when the nitride powder is produced by pulverization. Oxygen mixed in the nitride powder adversely affects semiconductors, so a nitride powder containing as little oxygen as possible is desired.
SUMMARY OF THE INVENTION An object of the present invention is to provide a method for pulverizing nitride in which contamination of oxygen during pulverization is suppressed.

The present inventors have found that by pulverizing the nitride in the presence of an oxygen absorbent made of a specific metal compound, the inclusion of oxygen into the nitride during pulverization can be suppressed.

That is, the present invention provides the following [1] to [6].
[1] Nitrides containing one or more elements selected from Groups 5, 13 and 14 of the periodic table, nitrides and amides of metals selected from Groups 1 and 2 of the periodic table A method for pulverizing nitrides, comprising pulverizing in the presence of one or more oxygen absorbents selected from imides and hydrides.
[2] The method for pulverizing nitrides according to [1] above, wherein the nitride is selected from tantalum nitride, aluminum nitride, indium nitride, gallium nitride and silicon nitride.
[3] The method for pulverizing nitride according to [1] or [2], wherein the amount of the oxygen absorbent used is 1 to 30% by mass relative to the nitride.
[4] The method for pulverizing the nitride according to any one of [1] to [3] above, wherein the nitride is pulverized using a mill.
[5] The method for pulverizing nitride according to any one of [1] to [4], wherein after pulverization, the pulverized material is washed with hydrochloric acid or nitric acid.
[6] The method for pulverizing nitride according to any one of [1] to [5] above, wherein the nitride has an average particle size of 30 μm or less after pulverization.

According to the present invention, it is possible to provide a method for pulverizing nitride in which contamination of oxygen during pulverization is suppressed.

The present invention will be described in detail below.
In the pulverization method of the present invention, a nitride having one or more elements selected from Groups 5, 13 and 14 of the periodic table is obtained from metals selected from Groups 1 and 2 of the periodic table, The material is pulverized in the presence of one or more oxygen absorbents selected from nitrides, amides, imides and hydrides.

(nitride)
The nitride used in the present invention is a nitride containing one or more elements selected from Groups 5, 13 and 14 of the periodic table. Nitrides may be synthesized from elements of groups 5, 13 and 14 of the periodic table, or may be commercially available. A well-known method can be adopted as a method for synthesizing the nitride.

Examples of nitrides containing elements of Group 5 of the periodic table include vanadium nitride, niobium nitride, and tantalum nitride.
Examples of nitrides containing elements of Group 13 of the periodic table include boron nitride, aluminum nitride, gallium nitride, indium nitride, and thallium nitride.
Examples of nitrides containing elements of Group 14 of the periodic table include silicon nitride, germanium nitride, and tin nitride.
Examples of nitrides containing two or more elements selected from Groups 5, 13 and 14 of the periodic table include indium gallium nitride, indium aluminum nitride, aluminum gallium nitride, aluminum gallium indium nitride, and indium aluminum gallium nitride. can be mentioned.
Among them, tantalum nitride, aluminum nitride, indium nitride, gallium nitride, and silicon nitride are preferable as the nitride because the effects of the present invention can be easily obtained.

(oxygen absorbent)
The oxygen absorbent has the function of absorbing and removing very little oxygen in the grinding atmosphere.
Oxygen absorbers include alkali metal nitrides, alkali metal amides, alkali metal imides, alkali metal hydrides, alkaline earth metal nitrides, alkaline earth metal amides, alkaline earth metal imides and alkaline earth metal hydrides. One or two or more selected can be appropriately selected and used.
Examples of alkali metal nitrides include lithium nitride (Li ₃ N), sodium nitride (Na ₃ N), and potassium nitride (K ₃ N).
Examples of alkali metal amides include lithium amide (LiNH ₂ ), sodium amide (NaNH ₂ ) and potassium amide (KNH ₂ ).
Examples of alkali metal imides include lithium imide (Li ₂ NH), sodium imide (Na ₂ NH), and potassium imide (K ₂ NH).
Examples of alkali metal hydrides include lithium hydride (LiH), sodium hydride (NaH), and potassium hydride (KH).

Examples of alkaline earth _metal nitrides include calcium nitride ( _Ca3N2 ), magnesium nitride ( _Mg3N2 ), _strontium nitride ( _Sr3N2 ), and barium nitride ( _{Ba3N2 ) .} can.
Alkaline earth metal amides include, for example, calcium amide (Ca(NH ₂ ) ₂ ), magnesium amide (Mg(NH ₂ ) ₂ ), strontium amide (Sr(NH ₂ ) ₂ ), barium amide (Ba(NH ₂ ) ₂ ) can be mentioned.
Examples of alkaline earth metal imides include calcium imide (CaNH), magnesium imide (MgNH), strontium imide (SrNH), and barium imide (BaNH).
Examples of alkaline earth metal hydrides include calcium hydride ( _CaH2 ), magnesium hydride ( _MgH2 ), strontium hydride ( _SrH2 ), and barium hydride ( _BaH2 ).

Among them, the oxygen absorbent is preferably one or more selected from alkali metal nitrides, alkali metal hydrides, alkaline earth metal nitrides, and alkaline earth metal hydrides, and lithium nitride (Li ₃ N ), sodium nitride, potassium nitride, lithium hydride, sodium hydride, potassium hydride, calcium nitride, magnesium nitride, strontium nitride, calcium hydride, magnesium hydride, and strontium hydride.

The amount of the oxygen absorbent used is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, more preferably 5 to 15% by mass, relative to the nitride, from the viewpoint of suppressing contamination of oxygen during pulverization. preferable.

(crushing)
The pulverization of the nitride is performed in the presence of the oxygen absorbent, but it is sufficient that the nitride and the oxygen absorbent coexist during the pulverization, and the order of mixing the nitride and the oxygen absorbent is not particularly limited. .
Pulverization can use a pulverizer. The pulverizing device is not particularly limited as long as it can pulverize the nitride and can be sealed, but a medium pulverizing device can be used. Examples of the media pulverizer include mills, and specific examples include container-driven media mills such as planetary ball mills, ball mills, and disk mills. The material of the grinding media and the grinding vessel is not particularly limited as long as it can grind the nitride and can prevent the contamination of impurities.

The pulverization conditions can be appropriately set depending on the type of pulverizer, nitride, and production scale. The temperature during pulverization is normal temperature (20° C.±15° C.).

The atmosphere during pulverization is preferably an oxygen-free atmosphere. Examples of the oxygen-free atmosphere include an inert gas atmosphere, and specific examples include a nitrogen gas atmosphere, an argon gas atmosphere, a nitrogen-hydrogen mixed gas atmosphere, an argon-hydrogen mixed gas atmosphere, and the like. When using a nitrogen-hydrogen mixed gas or an argon-hydrogen mixed gas, it is preferable that the hydrogen content is 3 to 5% by volume.
To make the atmosphere during grinding into an oxygen-free atmosphere, for example, when using a mill, the gas phase in the grinding container is replaced in a glove box with an oxygen-free atmosphere, and then the grinding media are added to the grinding container. It may contain the nitride and oxygen absorber and seal the opening of the grinding media.

(post-processing)
After grinding, the nitride can be washed with hydrochloric or nitric acid. As a result, the oxygen absorbent contained in the pulverized material can be dissolved and removed.
The washing method is not particularly limited as long as the pulverized material can be brought into contact with hydrochloric acid or nitric acid. I don't mind.
The concentration of hydrochloric acid is usually 0.05-12N, preferably 0.1-6N. Further, the nitric acid concentration is usually 0.1 to 16N, preferably 1 to 8N.
The washing time can be appropriately set according to the type of nitride and the production scale, but for 1 kg of nitride, it is usually 1 to 300 minutes, preferably 5 to 30 minutes. The temperature for washing is usually room temperature (20° C.±15° C.).
After washing with hydrochloric acid or nitric acid, it may be further washed with water. Washing with water can be performed multiple times, and stirring may be performed.
After washing, the pulverized nitride may be recovered by filtration or the like and dried. Although the drying method is not particularly limited, for example, a hot air drying method and a cold air drying method can be mentioned.

In the nitride pulverized in this manner, contamination of oxygen during pulverization is suppressed. Specifically, the increase in oxygen in the nitride before and after pulverization (the amount of oxygen in the nitride after pulverization - the amount of oxygen in the nitride before pulverization) is usually 0.1% or less, preferably 0.07. % or less, more preferably 0.05% or less, and still more preferably 0.03% or less. The lower limit is not particularly limited, and may be 0%. The oxygen concentration in the nitride can be measured using, for example, an oxygen-nitrogen simultaneous analyzer, and for example, TCH-600 manufactured by LECO can be used.

In addition, the nitride after pulverization preferably has an average particle size of 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. Although the lower limit of the average particle size is not particularly limited, it is preferably 0.1 μm or more, more preferably 1 μm or more, from the viewpoint of production efficiency. Here, the "average particle size" in this specification refers to the particle size distribution of a sample in accordance with JIS R 1629 "Method for measuring particle size distribution of fine ceramic raw materials by laser diffraction/scattering method". means the particle diameter (d ₅₀ ) corresponding to 50% of the cumulative distribution curve. For example, Microtrac MT3300EX II (manufactured by Microtrac Bell) can be used as a particle size distribution measuring device using a laser diffraction/scattering method.

EXAMPLES The embodiments of the present invention will now be described more specifically with reference to Examples. However, the present invention is not limited to the following examples.

1. Measurement of Oxygen Concentration The oxygen concentration was measured using an oxygen-nitrogen simultaneous analyzer (TCH-600, manufactured by LECO).

2. Measurement of Average Particle Size The particle size distribution of gallium nitride was prepared on a volume basis in accordance with JIS R 1629 "Method for measuring particle size distribution of fine ceramic raw materials by laser diffraction/scattering method". Then, the particle diameter (d ₅₀ ) corresponding to 50% of the integrated distribution curve was obtained. Microtrac MT3300EX II (manufactured by Microtrac Bell) was used as a particle size distribution measuring device by a laser diffraction/scattering method.

Example 1
10 g of metallic gallium was weighed and placed in an alumina boat, which was set in a φ50 mm core tube. Next, the inside of the furnace core tube was evacuated and replaced with nitrogen gas, and the gas was switched to ammonia and flowed at 0.5 L/min for 15 minutes to create an ammonia atmosphere in the furnace core tube. Then, the temperature was raised to 1050° C. at a rate of temperature increase of 5° C./min, and then held for 12 hours for nitriding. After nitridation, it was slowly cooled to room temperature, and gallium nitride bulk was collected. The gallium nitride bulk had an oxygen concentration of 0.23%.

Next, 10 g of gallium nitride bulk and 1 g of calcium nitride (Ca ₃ N ₂ ) were each weighed in a glove box in an oxygen-free atmosphere, and then they were placed in a high chromium steel crushing ball (φ 10 mm) filled with 100 g of high chromium steel. Placed in a steel grinding vessel (125 cc) and sealed. Then, it was taken out from the glove box and pulverized with a planetary ball mill (P-5, manufactured by Fritsch Japan Co., Ltd.) at a rotation speed of 300 rpm for 10 minutes. After pulverization, the pulverized product was collected in a glove box with an oxygen-free atmosphere, and the calcium compound was dissolved in a 500 mL beaker using 300 mL of 3N hydrochloric acid while stirring. After dissolution, the solid matter was recovered by suction filtration. After the collected solid content was washed with 300 mL of pure water in a 500 mL beaker while stirring, the solid content was recovered by suction filtration. This water washing and recovery were repeated three times, and the recovered solid content was dried to obtain pulverized gallium nitride. Then, the oxygen concentration in the pulverized gallium nitride was measured to obtain the amount of oxygen increase before and after the pulverization. Also, the average particle size was measured. Table 1 shows the results.

Example 2
Gallium nitride bulk was produced by the same operation as in Example 1. The gallium nitride bulk had an oxygen concentration of 0.21%.
Next, a pulverized material was obtained by the same operation as in Example 1, except that 1 g of strontium nitride (Sr ₃ N ₂ ) was used instead of calcium nitride. Next, the pulverized product was placed in a 500 mL beaker and 300 mL of 3N hydrochloric acid was used to dissolve the strontium compound. After the dissolution, the solid matter was collected by suction filtration, washed with water, collected and dried in the same manner as in Example 1 to obtain pulverized gallium nitride. Then, the oxygen concentration in the pulverized gallium nitride was measured to obtain the amount of oxygen increase before and after the pulverization. Also, the average particle size was measured. Table 1 shows the results.

Example 3
Gallium nitride bulk was produced by the same operation as in Example 1. The gallium nitride bulk had an oxygen concentration of 0.24%.
Next, a pulverized material was obtained by the same operation as in Example 1, except that 1 g of strontium hydride (SrH ₂ ) was used instead of calcium nitride. Next, the pulverized product was placed in a 500 mL beaker and 300 mL of 3N hydrochloric acid was used to dissolve the strontium compound. After the dissolution, the solid matter was recovered by suction filtration, washed with water, recovered, recovered and dried in the same manner as in Example 1 to obtain pulverized gallium nitride. Then, the oxygen concentration of the pulverized gallium nitride cormorants was measured to determine the amount of oxygen increase before and after the pulverization. Also, the average particle size was measured. Table 1 shows the results.

Comparative example 1
Gallium nitride bulk was produced by the same operation as in Example 1. The gallium nitride bulk had an oxygen concentration of 0.24%.
Next, a pulverized product was obtained by the same operation as in Example 1, except that calcium nitride was not used. Then, the oxygen concentration in the pulverized gallium nitride was measured to obtain the amount of oxygen increase before and after the pulverization. Also, the average particle size was measured. Table 1 shows the results.

From Table 1, nitrides containing one or more elements selected from Groups 5, 13 and 14 of the periodic table are nitrides of metals selected from Groups 1 and 2 of the periodic table, It can be seen that by pulverizing in the presence of one or more oxygen absorbents selected from amides, imides and hydrides, a pulverized nitride in which contamination of oxygen during pulverization is suppressed can be obtained.

Claims (5)

Nitrides containing one or more elements selected from Groups 5, 13 and 14 of the periodic table, nitrides, amides, imides and nitrides of metals selected from Groups 1 and 2 of the periodic table A method for pulverizing nitrides, comprising pulverizing in an oxygen-free atmosphere in the presence of one or more oxygen absorbents selected from hydrides , and washing the pulverized material with hydrochloric acid or nitric acid . 2. The method of pulverizing nitride according to claim 1, wherein said nitride is selected from tantalum nitride, aluminum nitride, indium nitride, gallium nitride and silicon nitride. 3. The method for pulverizing nitride according to claim 1, wherein the amount of said oxygen absorbent used is 1 to 30% by mass with respect to said nitride. The method for pulverizing nitride according to any one of claims 1 to 3, wherein the pulverization is performed using a mill. The method for pulverizing nitride according to any one of claims 1 to 4 , wherein the nitride has an average particle size of 30 µm or less after pulverization.