Patent ID: 8894959

Claim:
A silicon production method comprising: a semiconductor grade silicon production step (step A) of producing semiconductor grade silicon on a heated substrate by feeding trichlorosilane vapor together with hydrogen gas into a deposition reactor having the heated substrate, a chlorosilane separation step (step B) of separating hydrogen and a chlorosilane from gas discharged from the step A, a disproportionation step (step C) of passing a mixture comprising a low-boiling-point silane component and tetrachlorosilane which is obtained in the step B through a chlorosilane disproportionation solid catalyst bed to produce a mixture having an increased proportion of trichlorosilane, a trichlorosilane separation step (step D) of obtaining trichlorosilane by distilling and purifying the mixture obtained in the step C, a collection step (step (E(i))) which comprises mixing a stream of the trichlorosilane obtained in step D, which contains chlorosilyl phosphine impurities, with hydrogen, decomposing said impurities by raising the average temperature of a reaction gas to over 800° C., depositing solar grade silicon, and collecting the solar grade silicon, a recycling step (step (E(ii))) which comprises recycling a separate stream of trichlorosilane obtained in step D, which is different from the stream used in step E(i), back to step A, and a replenishing step (step F) of replenishing a separately prepared chlorosilane to any of the steps A to E(i).