Patent ID: 8197783

Claim:
A method for producing, separating and recovering disilicon hexachloride from a conversion reaction process for producing trichlorosilane by reacting hydrogen with silicon tetrachloride discharged from a polycrystalline silicon production process, comprising: producing polycrystalline silicon using trichlorosilane and hydrogen as raw materials, by a reaction of formula (1): SiHCl 3 +H 2 →Si+3HCl and a reaction of formula (2): 4SiHCl 3 →Si+3SiCl 4 +2H 2 in a polycrystalline silicon reaction furnace; condensing a gas discharged from the polycrystalline silicon reaction furnace, including silicon tetrachloride, hydrogen chloride, dichlorosilane, disilicon hexachloride, unreacted trichorosilane, and hydrogen, to produce a first condensed liquid including the silicon tetrachloride, the dichlorosilane, the disilicon hexachloride, and the unreacted trichorosilane, and to separate the hydrogen and the hydrogen chloride; separating the silicon tetrachloride from the first condensed liquid by distillation; introducing the separated silicon tetrachloride and hydrogen to a conversion furnace; conversion reacting silicon tetrachloride to produce trichlorosilane by a reaction of formula (3): SiCl 4 +H 2 →SiHCl 3 +HCl and other chlorosilanes including disilicon hexachloride in the conversion furnace; condensing a mixed gas discharged from the conversion furnace, which includes trichlorosilane, unreacted silicon tetrachloride, and other chlorosilanes including disilicon hexachloride, to produce a second condensed liquid; separating trichlorosilane and silicon tetrachloride from the second condensed liquid by distillation; and recovering disilicon hexachloride by distillation.