Silicon seed crystal and method for producing silicon single crystal

Abstract

There are disclosed a silicon seed crystal which is composed of silicon single crystal and used for the Czochralski method, wherein oxygen concentration in the seed crystal is 15 ppma (JEIDA) or less, a silicon seed crystal which is used for the Czochralski method, wherein the silicon seed crystal does not have a straight body, and a method for producing a silicon single crystal by the Czochralski method comprising using said seed crystal, bringing a tip end of the seed crystal into contact with a silicon melt to melt the tip end of the seed crystal, with or without performing necking operation, and growing a silicon single crystal. The method is capable of improving the rate of success in making crystals dislocation-free and the productivity of single crystal rods regardless of the use of necking operation.

What is claimed is:  
     
         1 . A silicon seed crystal which is composed of silicon single crystal and used for the Czochralski method, wherein oxygen concentration in the seed crystal is 15 ppma (JEIDA) or less.  
     
     
         2 . The silicon seed crystal according to  claim 1 , wherein the silicon seed crystal has a shape having a sharp-pointed tip end, or a truncated sharp-pointed tip end.  
     
     
         3 . A silicon seed crystal which is used for the Czochralski method, wherein the silicon seed crystal does not have a straight body.  
     
     
         4 . The silicon seed crystal according to  claim 3 , wherein the seed crystal has a body shape selected from the group consisting of shapes of cone, pyramid, truncated cone, truncated pyramid, combination of cone and truncated cone, combination of cone and truncated pyramid, combination of pyramid and truncated pyramid, and combination of pyramid and truncated cone.  
     
     
         5 . The silicon seed crystal according to  claim 3 , wherein a part or all of side surface of the seed crystal is formed with curved surface.  
     
     
         6 . The silicon seed crystal according to  claim 4 , wherein a part or all of side surface of the seed crystal is formed with curved surface.  
     
     
         7 . The silicon seed crystal according to  claim 3 , wherein oxygen concentration in the seed crystal is 16 ppma (JEIDA) or less.  
     
     
         8 . The silicon seed crystal according to  claim 4 , wherein oxygen concentration in the seed crystal is 16 ppma (JEIDA) or less.  
     
     
         9 . The silicon seed crystal according to  claim 5 , wherein oxygen concentration in the seed crystal is 16 ppma (JEIDA) or less.  
     
     
         10 . A method for producing a silicon single crystal by the Czochralski method, comprising the steps of using a silicon seed crystal according to  claim 1 , bringing a tip end of the seed crystal into contact with a silicon melt to melt the tip end of the seed crystal, performing necking operation, and growing a silicon single crystal.  
     
     
         11 . A method for producing a silicon single crystal by the Czochralski method, comprising the steps of using a silicon seed crystal according to  claim 3 , bringing a tip end of the seed crystal into contact with a silicon melt to melt the tip end of the seed crystal, performing necking operation, and growing a silicon single crystal.  
     
     
         12 . A method for producing a silicon single crystal by the Czochralski method, comprising the steps of using a silicon seed crystal according to  claim 1 , bringing a tip end of the seed crystal into contact with a silicon melt to melt the tip end of the seed crystal, and growing a silicon single crystal without performing necking operation.  
     
     
         13 . A method for producing a silicon single crystal by the Czochralski method, comprising the steps of using a silicon seed crystal according to  claim 3 , bringing a tip end of the seed crystal into contact with a silicon melt to melt the tip end of the seed crystal, and growing a silicon single crystal without performing necking operation.