Apparatus and method for producing polycrystalline silicon having a reduced amount of boron compounds by venting the system with an inert gas
The invention concern an apparatus and a method for manufacturing polycrystalline silicon having a reduced amount of boron compounds. The invention feeds Ar gas in a trichlorosilane line, which connects a trichlorosilane (TCS) tank and a series of distillation units. The distillation units have a pressure transducer and a pressure independent control valve (PIC-V) positioned on a vent gas line for discharging vent gas from the distillation units. Ar gas is fed to the TCS line with higher pressure than the pressure set for opening the PIC-V. The TCS is distilled by the distillation units with continuously discharging vent gas from the distillation units.
1. An apparatus for manufacturing polycrystalline silicon having a reduced amount of boron compounds, comprising:
a fluidized-bed reactor for reacting metallurgical grade silicon with hydrogen chloride gas for producing trichlorosilane;
an inert gas feeding tank for feeding inert gas to a trichlorosilane line extending from the fluidized-bed reactor to a distillation unit;
the distillation unit for purifying the trichlorosilane having a vent gas line with a vent for continuously discharging vent gas from the distillation unit;
a pressure independent control valve located on the vent gas line discharging from the distillation unit; and
a reactor for depositing polycrystalline silicon on surfaces of silicon seed rods.
2. The apparatus for manufacturing polycrystalline silicon according to claim 1 , further comprising:
a trichlorosilane tank, for keeping a liquid trichlorosilane and for constantly feeding the trichlorosilane to the distillation unit, located between the fluidized-bed reactor and the distillation unit; and
an evaporator for vaporizing the trichlorosilane fed to the reactor.