Patent ID: 7691357

Claim:
A method for producing polycrystalline silicon comprising: (A) a CVD step of making trichlorosilane (TCS) react with hydrogen to make polycrystalline silicon deposit on a base material; (B) a chlorination step of making a by-product mixture which is produced in the CVD step and contains poly-silane represented by a chemical formula H 2(n+1)−m Cl m Si n (wherein n is an integer of 2 to 4 and m is an integer of 0 to 2(n+1)) to react with chlorine and forming tetrachlorosilane (STC) distillate; (C) a hydrogenation step of making tetrachlorosilane (STC) distillate formed in the chlorination step react with hydrogen into the trichlorosilane (TCS), and (D) a circulation step of making a distillate containing methyl chlorosilane (MeCS) formed in the hydrogenation step with residual carbon from the reactor or present in the silicon circulate to the chlorination step and forming a hyper-chlorinated methyl chlorosilane.