Patent ID: 8293076

Claim:
A method, comprising: reacting a tetrachlorosilane comprising substance with hydrogen at a temperature of from 400° C. to 1,200° C. to obtain a mixture comprising silane, monochlorosilane, dichlorosilane, and trichlorosilane; removing impurities which are electrically active in a semiconductor crystal from the mixture; separating the trichlorosilane from the silane, monochlorosilane and dichlorosilane to obtain purified trichlorosilane; circulating the silane, monochlorosilane and dichlorosilane obtained from said separating into said reacting; and supplying a second mixture comprising dichlorosilane and a poly-silane represented by H 2(n+1)-m Cl m Si n , which is a by-product produced by depositing polycrystalline silicon onto a substrate, to said reacting, wherein n is an integer of 2 to 4 and m is an integer of 0 to 2(n+1).