Patent ID: 8431032

Claim:
A method for preparation of polycrystalline silicon using a fluidized bed reactor wherein the fluidized bed reactor comprises a reactor tube in which a bed of silicon particles is formed and upper and lower spaces in the reactor tube are respectively defined as a reaction zone provided for silicon deposition by a silicon-containing reaction gas and a heating zone provided for heating the silicon particles, and which comprises: a silicon particle preparation step, wherein the reaction gas is supplied so that silicon deposition occurs on surfaces of the silicon particles in contact with the reaction gas, while silicon deposit is accumulated on an inner wall of the reactor tube; a silicon particle partial discharging step that follows the silicon particle preparation step, wherein, without requiring the supply of the reaction gas, a part of the silicon particles remaining inside the reactor tube is discharged out of the fluidized bed reactor so that the height of the bed of the silicon particles does not exceed the height of a reaction gas outlet; a silicon deposit removal step that follows the silicon particle partial discharging step, wherein, without requiring the supply of the reaction gas, the silicon deposit is removed by supplying an etching gas into the reaction zone; and a silicon particle replenishing step that follows the silicon deposit removal step, wherein silicon particles are replenished into the reactor tube.