Method for producing polycrystalline silicon

Abstract

The present invention provides a method for producing semiconductor-grade high-purity polycrystalline silicon in a dosed system, the method comprising recovering chlorosilane contained in reaction exhaust gas and circulating the recovered chlorosilane to resupply and reuse the recovered chlorosilane for polycrystalline silicon deposition reaction without discharging the recovered chlorosilane out of the system. The present invention employs a process design including: step D of obtaining chlorosilane with a reduced impurity content from recovered chlorosilane fractionated in step C; and a step of supplying the chlorosilane with a reduced impurity content, which is obtained in the step D, to step A which is a step of depositing polycrystalline silicon. The employment of this process design allows a process for producing semiconductor-grade high-purity polycrystalline silicon to accomplish removal of impurity compounds which would otherwise accumulate in recovered chlorosilane circulating in a deposition reaction system and thus to yield polycrystalline silicon of stable quality.

Dependencies are inferred from the claim text.