SLURRY-DESIGNATED SILICON NITRIDE POWDER AND METHOD FOR PRODUCING SAME, SILICON NITRIDE POWDER SLURRY FOR USE IN MOLD RELEASE AGENT AND METHOD FOR PRODUCING SAME, SILICON NITRIDE POWDER FOR USE IN MOLD RELEASE AGENT, MOLD RELEASE AGENT, AND POLYCRYSTALLINE-SILICON-CASTING MOLD AND METHOD FOR PRODUCING SAME

摘要

Provided are: a silicon nitride powder slurry for use in mold release material and capable of forming, on a polycrystalline silicon casting mold, a mold release layer which exhibits favorable mold release properties of a polycrystalline silicon ingot, and which exhibits favorable adhesion to the casting mold after casting the polycrystalline silicon ingot, without requiring use of an additive such as a binder, and without requiring execution of a baking step; a method for producing the same; a silicon nitride powder for mold release material; mold release material; a silicon nitride powder for a slurry use for obtaining the silicon nitride powder slurry for use in the mold release material; a method for producing the same; a polycrystalline silicon casting mold which exhibits favorable mold release properties of a polycrystalline silicon ingot; and a low-cost method for producing the same. The present invention pertains to a silicon nitride powder to be used in a slurry for forming a mold release layer of a polycrystalline silicon casting mold, wherein the specific surface area thereof is 5-50m 2 /g, the proportion of amorphous silicon nitride is 1.0-25.0 mass%, and the oxygen content is 0.6-2.5 mass%.