METHOD OF OBTAINING POLYCRYSTALLINE SILICON Russian patent published in 2008 - IPC C01B33/35 

FIELD: chemistry.

SUBSTANCE: invention can be applied in chemistry and electronics. Silicon rods are heated to temperature 1100÷1200 °C, tempered in hydrogen medium and etched with hydrogen chloride, formed as a result of reaction of silicon tetrachloride and hydrogen with molar ratio (2÷1):1. In preparing steam-gas mixture, hydrogen, silicon tetrachloride and trichlorsilane with molar ratio of hydrogen to trichlorsilanes (8÷10):1, are introduced into evaporator, and pressure 0.6÷0.8 MPa is supported. Hydrogen reduction is carried out at temperature 1100÷1200 °C, and silicon tetrachloride is hydrated with formation in reaction zone of additional amount of trichlorsilane. Going out steam-gas mixture is subjected to step-by-step condensation at temperature minus 50÷75 °C with discharge of chlorsilanes to rectification separation and purification from high-boiling chlorsilanes. Purified chlorsilanes (tetrachlorsilane ans trichlorsilane) are directed into evaporator for preparation of steam-gas mixture, hydrogen and calcium chloride are directed to sorption separation with dissolution of hydrogen chloride in absorbent and hydrogen release. Hydrogen after comprimation to 0.8÷1.0 MPa is directed for preparation of steam-gas mixture.

EFFECT: increase of trichlorsilane and polycrystalline silicon output with reduction of energy consumption.

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