Method of making high purity silicon nitride precursor

Abstract

A method of economically making silicon nitride precursor, comprising: (a) reacting silicon halide vapor with liquid ammonia at a situs (i.e., at a temperature of -20.degree. to +40.degree. C.) in an inert environment having a pressure equal to or greater than 35 psig, which environment is effectively devoid of organic contaminants, said reaction producing a mixture of precipitated silicon imide in liquid ammonia having dissolved ammonium halide; (b) extracting a portion of the mixture from the situs; and (c) separating the precipitate from the liquid of the portion. Preferably the silicon halide is SiCl.sub.4 and its vapor is brought into reaction with the liquid ammonia by way of a nonreactive carrier gas (N.sub.2 or argon). The proportioning of the SiCl.sub.4 and liquid ammonia is effective so that the exothermic heat of chloride-ammonia reaction substantially offsets the latent heat of vaporization of the ammonia into the residual carrier gas to provide a neutral heat balance or slight overall endothermic heat transfer.

Dependencies are inferred from the claim text.