System for purifying trichlorosilane and method for producing polycrystalline silicon

摘要

There is provided a technology for the purification of trichlorosilane in which it is not necessary to remove large quantities of chlorosilanes from the system in the production of high purity trichlorosilane from a hydrocarbon containing chlorosilane fraction, and in which also the reaction control can be easily performed. In the present invention, the step of converting hydrocarbons contained in a chlorosilane fraction into low-boiling-point materials by thermal decomposition in the purification system has been provided to easily separate the hydrocarbons. Thereby, the conversion of hydrocarbons into low-boiling-point materials by thermal decomposition and separation in the cycle of trichlorosilane purification is performed, and it is not necessary to precipitate a large amount of chlorosilanes out of the system. As a result, the efficiency of trichlorosilane production is increased and the problem of reduced polycrystalline silicon yield also does not occur.