| 摘要 |
PURPOSE:The reaction oven is pressure-reduced, ammonia and silane gas are fed with hydrogen gas an a carrier to effect the reactions at specific temperature to form alpha-type silicon nitride on the desired surface of the base material whereby an alpha-type silicon nitride layer with high durability to the silicon melt is obtained. CONSTITUTION:The base material 3 such as carbon is held with holder 2 which is inserted from the bottom into the CVD oven 1. The oven 1 is evacuated through pipe 6 and heated with heater 4 through high-frequency coil 5 up to 1,500-1,750 deg.C. Ammonia and silane gas are fed together with hydrogen gas as a carrier through pipes 7 and 8 at a certain rate to effect the reactions for a certain time whereby an about 0.5mm thick silicon nitride film is formed on the baser material 3. Through this process, an alpha-type silicon nitride of less than 1% porosity with high durability to silicon melt is formed. The product is suitable for use in the production of silicon single crystal.
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