| 摘要 |
PROBLEM TO BE SOLVED: To produce high purity silicon nitride powder which is suitable for electronic parts such as an implement for a semiconductor, a circuit board by a direct nitriding method with excellent mass-productivity. SOLUTION: A metallic silicon powder raw material in which the total of the group 3B and 5B (exclusive of nitrogen) elements is <=100 μg/g, and the total of the group 7B elements is <=50 μg/g, and having a mean particle diameter of 10 to 20 μm is nitrided so that temperature is gradually raised in an atmosphere containing nitrogen or nitrogen and ammonia under the partial pressure of nitrogen of 30 KPa or more, and the mean reaction rate is controlled to <=2.0%/hr, and also, the cumulative reaction ratio until a temperature reaches 1,300 deg.C is controlled to >=85%, and the obtained silicon nitride ingot is pulverized to produce the silicon nitride powder. |
