Silicon tetrachloride is used as an intermediate in the manufacture of polysilicon, an ultrapure form of silicon,[3] because its boiling point facilitates purification by repeated fractional distillation. It is reduced by hydrogen in the hydrogenation reactor to trichlorosilane (HSiCl3), which is used directly in the Siemens process or further reduced to silane (SiH4) and injected into the fluidized bed reactor. Silicon tetrachloride reappears in both processes as a by-product and is recycled in the hydrogenation reactor. Vapor phase epitaxy of hydrogen reduction of silicon tetrachloride at about 1250 °C has been accomplished:

Silicon chloride

4(grams) + 2 hours

2(g) → Si(s) + 4 HCl(g) at 1250°C[10]

The polysilicon produced is used in large quantities by the photovoltaic industry as wafers for conventional solar cells made of crystalline silicon, and also by the semiconductor industry as wafers.

Silicon tetrachloride can also be hydrolyzed to fumed silica. High-purity silicon tetrachloride is used in the manufacture of optical fibers. The grade should be free of hydrogen containing impurities such as trichlorosilane. Optical fibers are manufactured using processes such as MCVD and OFD, in which silicon tetrachloride is oxidized to pure silica in the presence of oxygen.

As a raw material for the production of fused silica.