Patent ID: 7771687

Claim:
A method for preparing polycrystalline silicon using a fluidized bed reactor, comprising: providing a fluidized bed reactor wherein a reactor tube is placed within a reactor shell so as to be encompassed by the reactor shell, whereby dividing an inner space of the reactor shell into an inner zone formed within the reactor tube and an outer zone formed in between the reactor shell and the reactor tube, wherein a silicon particle bed is formed and silicon deposition occurs in the inner zone while a silicon particle bed is not formed and silicon deposition does not occur in the outer zone; maintaining a difference between an outer zone pressure (Po) and an inner zone pressure (Pi) at a condition of 0 bar≦(Pi−Po)≦1 bar wherein an inner pressure controller is spatially connected to the inner zone through at least one means selected from the group consisting of a fluidizing gas inlet means, a reaction gas inlet means, a silicon particle outlet means and an inner zone connecting means, which are spatially connected to the silicon particle bed; and introducing an inert gas into the outer zone, whereby maintaining a substantially inert gas atmosphere in the outer zone.