Apparatus for directional solidification of silicon including a refractory material

Abstract

The present invention relates to an apparatus and method for purifying silicon using directional solidification. The apparatus can be used more than once for the directional solidification of silicon without failure. The apparatus and method of the present invention can be used to make silicon crystals for use in solar cells.

1 . (canceled) 
     
     
         2 . An apparatus for directional solidification of silicon, comprising:
 a directional solidification mold having one or more side walls and a bottom portion, the one or more side walls including a first material, and the bottom portion including a second material different from the first material;   an outer jacket; and   an insulating layer disposed at least partially between the directional solidification mold and the outer jacket, the insulating layer in contact with at least a portion of the directional solidification mold, at least a portion of an inner side surface of the outer jacket, and at least a portion of an inner bottom surface of the outer jacket, and wherein the bottom portion of the direction solidification mold is in contact with the inner bottom surface of the outer jacket.   
     
     
         3 . The apparatus of  claim 2 , wherein the insulating layer is not disposed between the bottom portion of the directional solidification mold and the inner bottom surface of the outer jacket. 
     
     
         4 . The apparatus of  claim 2 , wherein the first material includes a hot face refractory. 
     
     
         5 . The apparatus of  claim 2 , wherein the first material includes aluminum oxide. 
     
     
         6 . The apparatus of  claim 2 , wherein the second material includes a conducting refractory. 
     
     
         7 . The apparatus of  claim 2 , wherein the second material includes at least one of silicon carbide, graphite, copper, steel, stainless steel, and cast iron. 
     
     
         8 . The apparatus of  claim 2 , comprising a top layer in contact with at least a portion of a top surface of the directional solidification mold, the top layer including a slip-plane refractory. 
     
     
         9 . The apparatus of  claim 8 , wherein the top layer includes at least one of fused silicon dioxide, silicon dioxide, aluminum oxide, silicon nitride, and graphite. 
     
     
         10 . The apparatus of  claim 2 , wherein the bottom portion includes at least one appendage member along a side surface of the bottom portion. 
     
     
         11 . The apparatus of  claim 10 , wherein the one or more side walls includes at least one receiving slot configured to receive the at least one appendage member to secure the one or more side walls to the bottom portion. 
     
     
         12 . The apparatus of  claim 2 , wherein the insulating layer includes at least one of insulating brick, a refractory material, a mixture of refractory materials, insulating board, ceramic paper, and high temperature wool. 
     
     
         13 . The apparatus of  claim 2 , wherein the insulating layer comprises an inner layer and an outer layer. 
     
     
         14 . The apparatus of  claim 13 , wherein the inner layer includes a third material and the outer layer includes a fourth material different from the third material. 
     
     
         15 . The apparatus of  claim 2 , comprising one or more anchors extending through at least one of the insulating layer and the one or more side walls. 
     
     
         16 . The apparatus of  claim 15 , wherein the one or more anchors include at least one of steel, stainless steel, and cast iron. 
     
     
         17 . An apparatus for directional solidification of silicon, comprising:
 a directional solidification mold having one or more side walls and a bottom portion, the one or more side walls including a first material, and the bottom portion including a second material different from the first material;   an outer jacket;   an insulating layer disposed at least partially between the directional solidification mold and the outer jacket, the insulating layer in contact with at least a portion of the directional solidification mold, a portion of an inner side surface of the outer jacket, and at least a portion of an inner bottom surface of the outer jacket, and wherein the bottom portion of the direction solidification mold is in contact with the inner bottom surface of the outer jacket; and   a top heater, comprising:
 one or more heating members; 
 insulation; and 
 a top heater outer jacket. 
   
     
     
         18 . The apparatus of  claim 17 , wherein each of the heating members includes one of a heating element or an induction heater. 
     
     
         19 . The apparatus of  claim 18 , wherein the heating element includes at least one of silicon carbide, molybdenum disilicide, and graphite. 
     
     
         20 . The apparatus of  claim 17 , wherein the insulation includes at least one of insulating brick, a refractory material, a mixture of refractory materials, insulating board, ceramic paper, and high temperature wool. 
     
     
         21 . The apparatus of  claim 20 , wherein the top heater outer jacket includes stainless steel.