Method for the production of high purity silicon

摘要

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.