Process for the purification of chlorosilanes

摘要

The present invention relates to the purification of chlorosilanes. According to the claimed process, not only traces of boron compounds can be removed from the chlorosilanes, enabling them to be used for the direct preparation of semiconductor silicon, but also traces of impurities of heavy metals. The removal of these heavy metal traces is of particular importance in the purification of tetrachlorosilane to be used for the production of optical fibres. According to the claimed process, the chlorosilanes are brought into intimate contact with compounds having an Si-O-Si grouping in the presence of small amounts of hydrogen halide, and the chlorosilane is then distilled off. The compounds containing an Si-O-Si grouping include, according to the invention, chlorosiloxanes and finely divided SiO2. These compounds can also have been produced in situ by adding hydrochloric acid to the chlorosilane.