Fluidized bed reactor for production of high purity silicon

Abstract

Methods and apparatus for the production of high purity silicon including a fluidized bed reactor with one or more protective layers deposited on an inside surface of the fluidized bed reactor. The protective layer may be resistant to corrosion by fluidizing gases and silicon-bearing gases.

1 . A method of producing high purity silicon comprising:
 injecting at least one fluidizing gas into a fluidized bed reactor, wherein the fluidized bed reactor comprises:   a chamber constructed of a metal alloy, the chamber including a gas inlet and an effluent outlet;   a ceramic protective layer deposited on an inside surface of the chamber, wherein the ceramic protective layer comprises at least one of the following: alumina (Al 2 O 3 ) and zirconium dioxide (ZrO 2 );   a bed of silicon beads disposed within the chamber; and   at least one reactor heater;   injecting at least one silicon-bearing gas into the fluidized bed reactor,   heating the fluidized bed reactor with the at least one reactor heater to a temperature sufficient for thermal decomposition of silicon; and   collecting the high purity silicon that has been produced and deposited on the fluidized silicon beads;   wherein the ceramic protective layer is resistant to corrosion by the at least one fluidizing gas or the at least one silicon-bearing gas.   
     
     
         2 . The method of  claim 1 , wherein the metal alloy is an iron-based alloy selected from at least one of the following: a stainless steel alloy and a chromium-nickel alloy. 
     
     
         3 . The method of  claim 1 , wherein the metal alloy is a nickel-based alloy selected from at least one of the following: a nickel-molybdenum alloy and a nickelchromium-molybdenum alloy. 
     
     
         4 . The method of  claim 1 , further comprising an adhesion layer positioned between the protective layer and the inside surface of the chamber. 
     
     
         5 . The method of  claim 4 , wherein the adhesion layer comprises a nickel alloy layer, or a nickel-chromium-yttrium alloy layer. 
     
     
         6 . The method of  claim 1 , wherein the protective layer is deposited on the inside surface of the chamber by at least one of the following: thermal projection, chemical vapor deposition, physical vapor deposition, solgel, electrophoretic deposition and aerosol thermal spraying. 
     
     
         7 . The method of  claim 1 , wherein an external surface of the chamber is sandblasted to improve the thermal power transfer efficiency of the chamber compared to an untreated external surface. 
     
     
         8 . The method of  claim 1 , wherein the fluidizing gas is at least one of the following:
 hydrogen, helium, argon, silicon tetrachloride, silicon tetrabromide and silicon tetraiodide.   
     
     
         9 . The method of  claim 1 , wherein the silicon-bearing gas is at least one of the following: monosilane, disilane, trisilane, trichlorosilane, dichlorosilane, monochlorosilane, tribromosilane, dibromosilane, monobromosilane, triiodosilane, diiodosilane and monoiodosilane. 
     
     
         10 . The method of  claim 1 , wherein heating the fluidized bed reactor with the at least one reactor heater to a temperature sufficient for thermal decomposition of silicon comprises heating the fluidized bed reactor to a temperature of between approximately 500° C. to approximately 1200° C. 
     
     
         11 . The method of  claim 10 , wherein the fluidized bed reactor is heated to a temperature ranging from approximately 700° C. to approximately 900° C. 
     
     
         12 . A fluidized bed reactor for the production of high purity silicon, the fluidized bed reactor comprising:
 a chamber having dimensions to contain silicon particles capable of being fluidized therein, the chamber having a wall constructed of a metal alloy;   a gas inlet in the chamber configured to receive a gas to fluidize the particles inside the chamber, wherein the gas inlet is coupled to a source of silicon-bearing gas;   a silicon particle inlet configured for the addition of silicon particles into the chamber;   an outlet in the chamber configured to allow the recovery of the high-purity silicon;   an outlet configured to allow an effluent gas stream to leave the chamber; and   a ceramic protective layer deposited on at least a portion of an inside surface of the chamber wherein the ceramic protective layer comprises at least one of the following: alumina (Al 2 O 3 ) and zirconium dioxide (ZrO 2 ); and   wherein the ceramic protective layer is configured to be resistant to corrosion by the fluidizing gas.   
     
     
         13 . The fluidized bed reactor of  claim 12 , wherein the metal alloy is an iron-based alloy selected from at least one of the following: a stainless steel alloy and a chromium-nickel alloy. 
     
     
         14 . The fluidized bed reactor of  claim 13 , wherein the metal alloy further includes at least one of the following: manganese, molybdenum, silicon, cobalt and tungsten. 
     
     
         15 . The fluidized bed reactor of  claim 12 , wherein the metal alloy is a nickel-based alloy selected from at least one of the following: a nickel-molybdenum alloy and a nickel-chromium-molybdenum alloy. 
     
     
         16 . The fluidized bed reactor of  claim 15 , wherein the metal alloy further includes at least one of the following: manganese, molybdenum, silicon, cobalt and tungsten. 
     
     
         17 . The fluidized bed reactor of  claim 12 , further comprising an adhesion layer positioned between the protective layer and the inside surface of the chamber. 
     
     
         18 . The fluidized bed reactor of  claim 17 , wherein the adhesion layer comprises at least one of the following: a nickel alloy layer and a nickel-chromium-yttrium layer. 
     
     
         19 . The fluidized bed reactor of  claim 12 , wherein the ceramic protective layer deposited on the inside surface of the chamber is deposited by at least one of the following: thermal projection, chemical vapor deposition, physical vapor deposition, solgel, electrophoretic deposition and aerosol thermal spraying. 
     
     
         20 . The fluidized bed reactor of  claim 12 , wherein the chamber comprises an external surface and, wherein at least a portion of the external surface of the chamber has been treated to improve the thermal power transfer efficiency of the chamber compared to an untreated external surface. 
     
     
         21 . The fluidized bed reactor of  claim 20 , wherein the external surface of the chamber is sand-blasted to improve the thermal power transfer efficiency of the chamber. 
     
     
         22 . The fluidized bed reactor of  claim 12 , wherein the chamber is constructed of a material configured to withstand internal pressures ranging from approximately 50 mbar to approximately 5000 mbar. 
     
     
         23 . The fluidized bed reactor of  claim 12 , wherein the chamber is constructed of a material configured to withstand temperatures ranging from approximately 500° C. to approximately 1200° C. 
     
     
         24 . The fluidized bed reactor of  claim 12 , wherein the silicon particles comprise silicon beads and the gas comprises at least one of the following:
 hydrogen, helium, argon, silicon tetrachloride, silicon tetrabromide, silicon tetraiodide, monosilane, disilane, trisilane, trichlorosilane, dichlorosilane, monochlorosilane, tribromosilane, dibromosilane, monobromosilane, triiodosilane, diiodosilane and monoiodosilane.   
     
     
         25 . The fluidized bed reactor of  claim 12 , further comprising at least one reactor heater, wherein the at least one reactor heater comprises at least one of the following: a radiation heater and a conduction heater. 
     
     
         26 . A fluidized bed reactor used in the production of high-purity silicon, comprising:
 a chamber having dimensions to receive silicon beads capable of being fluidized therein, the chamber having a wall constructed of a metal alloy;   a gas inlet in the chamber configured to receive a fluidizing gas and a silicon-bearing gas to fluidize the particles inside the chamber, wherein the gas inlet is coupled to a source of the fluidizing gas and the silicon-bearing gas;   an outlet in the chamber configured to allow a recovery of the high-purity silicon; an outlet configured to allow an effluent gas stream to leave the chamber; and   a protective layer deposited on at least a portion of an inside surface of the chamber wherein the protective layer comprises at least one of the following: alumina (Al 2 O 3 ) and zirconium dioxide (ZrO 2 ).