Method for production of high purity silicon

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 (SiCl4), hydrogen (H2) 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 (SiHCl3) 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 SiCl4 and a partial stream, essentially comprising SiHCl3, c) disproportionation of the SiHCl3-containing partial stream to give SiCl4 and SiH4, 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 SiHCl3 is introduced into a first reaction zone, the lower boiling SiH4-containing disproportionation product produced there undergoes an intermediate condensation in a temperature range of −25° C. to 50° C., the non-condensing SiH4-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 SiH4 is completely or partially condensed in the head condenser and d) thermal decomposition of the SiH4 to give high purity silicon.

Dependencies are inferred from the claim text.