Systems For Insulating Directional Solidification Furnaces

Abstract

Systems and methods are disclosed for inhibiting heat transfer through lateral sidewalls of a support member positioned beneath a crucible in a directional solidification furnace. The systems and methods include the use of insulation positioned adjacent the lateral sidewalls of the support member. The insulation inhibits heat transfer through the lateral sidewalls of the support member to ensure the one-dimensional transfer of heat from the melt through the support member.

1 . A directional solidification furnace comprising:
 a crucible for holding molten silicon;   a crucible support supporting the crucible and transmitting heat therethrough;   a support member in thermal communication with the crucible support, the support member having an upper surface disposed adjacent the crucible support, a lower surface and lateral sidewalls; and   an insulating member disposed adjacent the lateral sidewalls of the support member to insulate the lateral sidewalls such that heat is inhibited from exiting therethrough.   
     
     
         2 . The furnace of  claim 1  wherein the insulation is in contact with the lateral sidewalls of the support member. 
     
     
         3 . The furnace of  claim 1  wherein the support member is rectangular and has four lateral sidewalls. 
     
     
         4 . The furnace of  claim 3  wherein the insulating member comprises four sections, each of the four sections positioned adjacent a respective lateral sidewall of the support member. 
     
     
         5 . The furnace of  claim 4  wherein each of the four sections of the insulating member is in contact with the respective lateral sidewall of the support member. 
     
     
         6 . The furnace of  claim 3  wherein the insulating member has a main portion generally parallel to the lateral sidewalls of the support member and a secondary portion generally perpendicular to the main portion. 
     
     
         7 . The furnace of  claim 6  wherein a side of the secondary portion is in contact with the crucible support. 
     
     
         8 . The furnace of  claim 6  wherein the main portion and the secondary portion are separate from each other and connected to form the insulating member. 
     
     
         9 . The furnace of  claim 6  wherein the main portion and the secondary portion are regions of the insulating member and the insulating member is a continuous structure. 
     
     
         10 . A directional solidification furnace comprising:
 a crucible for holding molten silicon;   a crucible support for supporting the crucible, the crucible support having a lower surface;   a support member having an upper surface and a lower surface connected along their respective peripheries by lateral sidewalls, the lower surface of the crucible support positioned adjacent the upper surface of the support member, the lateral sidewalls having a height;   a main insulating member positioned adjacent the lateral sidewalls of the support member, the main insulating member having a height greater than or equal to the height of the lateral sidewalls of the support member, the main insulating member reducing the amount of heat transferred through the lateral sidewalls of the support member; and   a secondary insulating member positioned atop the main insulating member and adjacent the crucible support, the secondary insulating member ensuring a view factor is not present between the support member and other components of the directional solidification furnace.   
     
     
         11 . The furnace of  claim 10  wherein the main insulating member is in contact with the lateral sidewalls of the support member. 
     
     
         12 . The furnace of  claim 10  wherein at least a portion of the secondary insulating member is in contact with the crucible support. 
     
     
         13 . The furnace of  claim 10  wherein the main insulating member is movable between a first position where the main insulating member is in contact with the lateral sidewalls of the support member and a second position where the main insulating member is disposed away from the lateral sidewalls of the support member. 
     
     
         14 . The furnace of  claim 10  wherein the secondary insulating member is movable between a first position where the secondary insulating member is in contact with the crucible support and a second position wherein the secondary insulating member is disposed away from the crucible support. 
     
     
         15 . A directional solidification furnace comprising:
 a crucible for holding molten silicon;   a crucible support for supporting the crucible, the crucible support having a lower surface;   a support member having an upper surface and a lower surface connected along their respective peripheries by lateral sidewalls, the lower surface of the crucible support positioned adjacent the upper surface of the support member;   insulation positionable between a first position where the insulation is adjacent the lateral sidewalls of the support member and a second position where the insulation is disposed away from the lateral sidewalls of the support member.   
     
     
         16 . The furnace of  claim 15  wherein the insulation is in contact with the lateral sidewalls of the support member when in the first position. 
     
     
         17 . The furnace of  claim 15  wherein the insulation is not in contact with the lateral sidewalls of the support member when in the second position. 
     
     
         18 . A method of adjusting the position of insulation in a directional solidification furnace, the furnace including a crucible for holding molten silicon, a crucible support for supporting the crucible, the crucible support having a bottom plate, a support member having an upper surface in contact with the bottom plate of the crucible support, the support member having lateral sidewalls, the method comprising:
 positioning the insulation in a first position during solidification of molten silicon in the crucible, wherein the insulation is adjacent the lateral sidewalls of the support member when in the first position; and   positioning the insulation in a second position during melting of the silicon in the crucible, wherein the insulation is disposed away from the lateral sidewalls of the support member when in the second position.   
     
     
         19 . The method of  claim 18  wherein when in the first position, the insulation is in contact with the lateral sidewalls of the support member. 
     
     
         20 . The method of  claim 18  wherein when in the second position, the insulation is not in contact with the lateral sidewalls of the support member.