Patent ID: 6887448

Claim:
A method for producing high-purity silicon, characterized by the following steps: a) reaction of metallic silicon with silicon tetrachloride (SiCl 4 ), hydrogen (H 2 and hydrochloric acid (HCl) at a temperature of 500 to 800Â° C. and a pressure of 25 to 40 bar to give a trichlorosilane-containing (SiHCl 3 ) feed gas stream, b) removal of impurities from the resultant of trichlorosilane containing feed gas stream by scrubbing with condensed chlorosilanes at a pressure of 25 to 40 bar and a temperature from 160 to 220Â° C. in a multi-stage distillation column, to give a purified trchlorosilane containing feed gas stream and a solid containing chlorosilane suspension, and distillative separation of the purified feed gas stream into a partial stream essentially comprising SiCl 4 and a partial stream essentially comprising SiHCl 3 , c) disproportionation of the SiHCl 3 -containing partial stream to give SiCl 4 and SiH 4 , whereby the disproportionation is carried out in several reactive/distillative reaction zones, with a counter-current of vapor and liquid, on catalytically active solids at a pressure of 500 mbar to 50 bar and SiHCl 3 , is introduced into a first reaction zone, the lower-boiling SiH 4 -containing disproportionation product produced there undergoes an intermediate condensation in a temperature range of âˆ’25 to 50Â° C., the non-condensed SiH 4 -containing product mixture is fed to one or more further reactive/distillative reaction zones and the lower boiling point product thus generated, containing a high proportion of SiH 4 is completely or partially condensed in the top condenser, and d) thermal decomposition of the SiH 4 to give high-purity silicon.