Silicon tetrachloride is the inorganic compound with the formula SiCl4. It is a colourless volatile liquid that fumes in air. It is used to produce high purity silicon and silica for commercial applications.
Silicon Tetarchloride Producion
Silicon tetrachloride is prepared by the chlorination of various silicon compounds such as ferrosilicon, silicon carbide, or mixtures of silicon dioxide and carbon. The ferrosilicon route is most common.
In the laboratory, SiCl4 can prepared by treating silicon with chlorine:
Si + 2 Cl2 → SiCl4
Silicon tetrachloride is used as an intermediate in the manufacture of high purity silicon, since it has a boiling point convenient for purification by repeated fractional distillation. It can be reduced to silicon by hydrogen gas. Very pure silicon derived from silicon tetrachloride is used in large amounts in the semiconductor industry, and also in the production of photovoltaic cells. It can also be hydrolysed to high purity fused silica. High purity silicon tetrachloride is used in the manufacture of optical fibres. This grade should be free of hydrogen containing impurities like trichlorosilane. Optical fibres are made using processes like MCVD and OFD where silicon tetrachloride is oxidized to pure silica in the presence of oxygen.