METHOD OF PRODUCING HIGH-PURITY POLYCRYSTALLINE SILICON Russian patent published in 2020 - IPC C01B33/03 C01B33/35 C30B28/14 C30B29/04 

FIELD: chemical or physical processes.

SUBSTANCE: invention relates to chemical technology of producing polycrystalline silicon by hydrogen reduction of trichlorosilane with hydrogen to silicon core bars in a waste-free mode. Method involves preparation of initial vapor-gas mixture in evaporator SiHCl₃ 1 by hydrogen bubbling through a layer of trichlorosilane with molar ratio H₂:SiHCl₃ = (3.0–3.5):1 with its further supply to reduction reactor 2, where polycrystalline silicon is deposited on heated to 1100–1150 °C silicon rods, supply of vapor-gas mixture recovery reactor 2, consisting of hydrogen, silicon tetrachloride, trichlorosilane and hydrogen chloride, into waste heat reactor 3, in which at temperature of 315–350 °C separation of hydrogen chloride from the vapor-gas mixture leaving reduction reactor 2 to obtain a mixture of hydrogen, trichlorosilane and silicon tetrachloride in ratio SiHCl₃/SiCl₄= 50 %/50 %, then obtained mixture is fed into membrane separation unit 4 for separation of hydrogen on polymer membranes at heating temperature of up to 100 °C and pressure drop of 8 atm, which is returned to the evaporator of SiHCl₃ 1, and mixture of trichlorosilane and silicon tetrachloride is subjected to condensation 5 and rectification 6, after which trichlorosilane is returned to the evaporator of SiHCl₃ 1, and silicon tetrachloride is supplied to the evaporator of SiCl₄ 7, in which hydrogen is bubbled through a layer of silicon tetrachloride to form a vapor-gas mixture with molar ratio H₂:SiCl₄ = (3.0–6.5):1, which is then fed into plasma-chemical reactor 8 for synthesis of trichlorosilane, wherefrom a gas-vapor mixture consisting of hydrogen, silicon tetrachloride, trichlorosilane and hydrogen chloride, is directed to a waste heat reactor 3 for separation of hydrogen chloride. Therefore, all components are used in production without generation of wastes or emissions into atmosphere.

EFFECT: result is reduced power consumption, increased quality of silicon, environmental safety, reduced consumption of reagents per unit of production.

3 cl, 1 dwg, 1 ex