| abstract |
The invention relates to a method for the production of 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 800° 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 trichlorosilane-containing feed gas stream by scrubbing with condensed chlorosilanes at a pressure of 25 to 40 bar and a temperature of 160 to 200° C. in a multi-stage distillation column, to give a purified trichlorosilane-containing feed gas stream and a solid-containing chlorosilane suspension and a 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 vapour and liquid, on catalytic 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 −25° C. to 50° C., the non-condensing SiH 4 -containing product mixture is fed to one or more further reactive/distillative reaction zones and the lower boiling product thus generated, containing a high proportion of SiH 4 is completely or partially condensed in the head condenser and d) thermal decomposition of the SiH 4 to give high purity silicon. |