Patent ID: 8821827
Filing Date: 2014-09-02
Classification: C01B,C23C

Abstract:
1. An apparatus for preparing granular polysilicon comprises: a reactor tube, an inner space of which comprises a heating zone and a reaction zone above the heating zone, wherein the inner space comprises an inner zone where the bed of silicon particles is present and silicon deposition occurs; a reactor shell enclosing the reactor tube, wherein a space in between the reactor tube and the reactor shell comprises an outer zone where the bed of silicon particles is not present and silicon deposition does not occur; an inert gas connecting means that maintains a substantially inert gas atmosphere in the outer zone; a pressure controlling means that measures and/or controls an inner zone pressure (Pi) and/or an outer zone pressure (Po), and a pressure-difference controlling means that maintains the difference in the outer zone pressure (Po) and the inner zone pressure (Pi) in the range of about 0.01 bar to about 1 bar; a fluidizing gas supplying means that supplies a fluidizing gas for fluidizing the bed of silicon particles to a bottom of the heating zone, and comprises a gas distribution means for distributing the fluidizing gas across the cross-section at the bottom of the heating zone, wherein the gas distribution means comprises a gas distribution plate or a gas distribution assembly having a plurality of holes and/or nozzles that are arranged to distribute the fluidizing gas across the cross-section at the bottom of the heating zone; a reaction gas supplying means installed within the bed of silicon particles and supplying a reaction gas required for silicon deposition into the bed of silicon particles; an internal heater installed in a space in between the reaction gas supplying means and the inner wall of the reactor tube, wherein the internal heater and the reaction gas supplying means are installed vertically from the gas distribution means through the cross-section at the bottom of the heating zone, the internal heater and the reaction gas supplying means intersecting with the gas distribution means, such that the gas distribution plate or the gas distribution assembly surrounds the intersection of the internal heater with the gas distribution means, and surrounds the intersection of the reaction gas supplying means with the gas distribution means; a gas discharging means discharging an off-gas out of the reactor shell; and a particle discharging means discharging a part of the silicon particles prepared in the reactor tube, wherein the height of the reaction gas outlet is located higher than the fluidizing gas outlets, is selected as the reference height for dividing the reaction zone and the heating zone, and the height of the internal heater is higher than the fluidizing gas outlets, but not higher than the reaction gas outlet, for heating the fluidizing gas and the silicon particles in the heating zone.