Method and apparatus for preparing polysilicon granules

Abstract

The present invention relates to a method and an apparatus for preparing polysilicon, more specifically to a method and an apparatus for preparing polysilicon in granule form by equipping a fluidized bed reactor with a nozzle that provides an etching gas including hydrogen chloride in order to effectively prevent silicon from depositing on the outlet surfaces of the reaction gas supplying means and to be able to operate the reactor continuously in the bulk production of polysilicon granules.

What is claimed is:  
     
         1 . A method for preparing polysilicon by supplying reaction gas in a fluidized bed reactor, wherein an etching gas including hydrogen chloride is injected on the surfaces of a reaction gas supplying means of the fluidized bed reactor.  
     
     
         2 . The method for preparing polysilicon according to  claim 1 , wherein said etching gas is prepared by adding an inert gas to said hydrogen chloride.  
     
     
         3 . The method for preparing polysilicon according to  claim 2 , wherein said hydrogen chloride is separated and recovered from the off-gas out of said reactor.  
     
     
         4 . The method for preparing polysilicon according to  claim 2 , wherein said inert gas is selected from hydrogen, nitrogen, argon, helium, and a mixture thereof.  
     
     
         5 . An apparatus for preparing polysilicon which includes a fluidized bed reactor comprising a fluidizing gas supplying means equipped with a gas distributor and a reaction gas supplying means equipped with a reaction gas nozzle, wherein said reaction gas nozzle is installed in a coaxial double-pipe form inside an etching gas nozzle for supplying said etching gas on the surfaces of said reaction gas nozzle.  
     
     
         6 . The apparatus for preparing polysilicon according to  claim 5 , wherein said reaction gas nozzle and said etching gas nozzle are made of quartz, silica, silicon nitride, surface-oxidized silicon, or carbon or silicon carbide coated with said materials.  
     
     
         7 . The apparatus for preparing polysilicon according to  claim 5 , wherein the elevations of the outlets of said reaction gas nozzle and said etching gas nozzle are the same or different within the range of 10-30 mm.  
     
     
         8 . The apparatus for preparing polysilicon according to  claim 5 , wherein the annular space between said etching gas nozzle and said reaction gas nozzle is filled with a stationary filler.  
     
     
         9 . The apparatus for preparing polysilicon according to  claim 8 , wherein the material of said stationary filler is selected from quartz, silica, silicon nitride, surface-oxidized silicon, carbon coated with said materials, silicon carbide coated with said materials, and a mixture thereof.