METHOD FOR MANUFACTURING POLYSILICON AND METHOD FOR MANUFACTURING SILICON TETRACHLORIDE

摘要

A process for production of polysilicon and silicon tetrachloride is provided in which a raw material that is supplied stably and is available at low cost can be used, chlorination reaction can be smoothly promoted, impurities generated after chlorination reaction can be controlled, and production efficiency is superior in a polysilicon producing step. The process includes a step of chlorination in which a granulated body consisting of silicon dioxide and carbon-containing material is chlorinated to generate silicon tetrachloride, a step of reduction in which silicon tetrachloride is reduced by a reducing metal to generate polysilicon, and a step of electrolysis in which chloride of the reducing metal by-produced in the reduction step is molten salt-electrolyzed to generate the reducing metal and chlorine gas. In the process, chlorine gas is supplied to the silicon dioxide and the carbon-containing material in the presence of oxygen gas, and these are reacted in the chlorination step, the reducing metal generated in the electrolysis step is reused in the reduction step as a reducing agent of silicon tetrachloride, and the chlorine gas generated in the electrolysis step is reused in the chlorination step.