High-purity silicon tetrachloride

Reuse of by-products【recovery process】

By-products in the reduction process for the manufacture of polycrystalline silicon include silicon tetrachloride and hydrogen gas. The silicon tetrachloride is reused as a feedstock for making trichlorosilane in the conversion process, but part of it is refined over and over again to make it ultra-pure, and shipped as a material for making products such as precision optical lenses. The hydrogen gas, the other by-product in the reduction process, is used as a feedstock for the conversion process, and is also reused in the reduction process.

Silicon tetrachloride production

The process for reducing trichlorosilane with hydrogen produces polycrystalline silicon and also a gas that includes unreacted trichlorosilane, hydrogen chloride, and silicon tetrachloride. This gas is cooled to recover various components individually, and among of them, silicon tetrachloride is highly purified by distillation.

Applications of Silicon tetrachloride

Our ultra-pure silicon tetrachloride can be utilized for uses such as a material for the manufacture of precision optical lenses, a material for the manufacture of synthetic quartz, and as a photomask for semiconductor manufacture. It is also used for optical fibers.

Purity/analysis

（e.g. semiconductor grade）

Contaminant	Purity	Method of analysis
n-type contaminants (mainly phosphorus）	≦0.5ppba	Photoluminescence measurement of a single crystal
p-type contaminants (mainly boron）	≦0.3ppba	Photoluminescence measurement of a single crystal
SiHCl3	≦5.0ppmw	Gas chromatograph（detection limit 5.0 ppmw）
Purity	≧99.99％	Gas chromatograph

Physical properties

Boiling point	Melting point	Specific gravity
57℃	-70℃	1.48（20℃）

Packaging