GB1263972A - Purification of chlorosilane hydrides - Google Patents

Abstract

1,263,972. Purification of chlorosilane hydrides. P. K. TAYLOR (Union Carbide Corp.). 7 Feb., 1969 [7 Feb., 1968], No. 6625/69. Heading C1A. Boron impurities are removed from chlorosilane hydrides containing only silicon, chlorine and hydrogen (i.e. SiH a Cl b wherein a and b are integers 1 to 3 and a+b=4) by dispersing preformed partial hydrolyzates of a chlorosilane in a clear non-turbid liquid body of the chlorosilane hydride and thereafter separating the chlorosilane hydride from the partial hydrolyzates and from boron in combination therewith. The partial hydrolyzates which may -be colloidal are formed by reacting a chlorosilane vapour with water vapour and are compounds containing one or two silicon bonded hydroxyl groups. The chlorosilane vapour and water vapour may be reacted in a zone apart,from the liquid body and then introduced thereto e.g. in a stream of inert gas or the reaction may be carried out in a zone contiguous to the liquid body i.e. the vapour phase above the liquid body. The separation of the partial hydrolyzates and. the hydride may be by distillation, dialysis or decantation. The concentration of the boron impurities into the partial hydrolyzate may be made use of in the analysis of the boron content of a chlorosilane hydride, all the boron content being concentrated into a small quantity of high boiling point, apparently hydrolysed boron compounds, which may be analyzed, e.g. by colorimetric methods. The purified chlorosilane hydride is suitable for the production ;of semi-conductor grade silicon, e.g. by reduction with hydrogen, zinc, sodium or metal hydrides.