Trichlorosilane purification system and method for producing polycrystalline silicon

摘要

There is provided trichlorosilane purification technology in which it is unnecessary to discharge large amounts of chlorosilanes oat of the system in the production of high-purity trichlorosilane from a chlorosilane fraction containing hydrocarbons and in which the reaction control can also be easily performed. In the present invention, the step of converting hydrocarbons contained in a chlorosilane fraction into low-boiling materials by thermal decomposition has been provided in the purification system in order to easily separate the hydrocarbons. Thereby, the conversion of hydrocarbons into low-boiling materials by thermal decomposition and the separation are performed in the trichlorosilane purification cycle, and it is unnecessary to discharge large amounts of chlorosilanes out of the system. As a result, the trichlorosilane production efficiency is increased, and the problem of yield reduction of polycrystalline silicon does not arise either.