POLYCRYSTALLINE SILICON PRODUCTION PROCESS Russian patent published in 1999 - IPC

FIELD: silicon production. SUBSTANCE: invention can be used in production of polycrystalline silicon via hydrogen reduction of trichlorosilane into silicon rods and includes preliminary purification of hydrogen and trichlorosilane, preparation of gas-vapor mixture in evaporator, deposition of silicon on hot silicon rods in reduction reactor, regeneration of leaving gas-vapor mixture components by fractional condensation of chlorosilanes and hydrogen chloride, and recycling unreacted trichlorosilane and hydrogen. According to invention, starting mixture is prepared by bubbling hydrogen through trichlorosilane layer in evaporator, leaving gas-vapor mixture, prior to be fractionally condensed, is subjected to liquid compression to produce pressure in apparatus system sufficient to carry out recycling feeding of mixture into reduction reactor. Chlorosilane condensate from partial condensation zone is rectified to give separated trichlorosilane and silicon tetrachloride. Amount of gas-vapor mixture fed into reactor is proportional to surface of silicon rods before feeding and is found from following equations: . Rods are subjected to preliminary (starting) plasma-heating using nitrogen as plasma-forming gas and then etched with hydrogen chloride obtained after fractional condensation of gas-vapor mixture. After the end of reduction process, remaining polychlorides are removed from reactor walls with 1:1 silicon tetrachloride-hydrogen mixture. EFFECT: reduced consumption of power and reagents. 9 cl, 1 dwg