Method of manufacturing composite crucible and method of manufacturing silicon crystal

Abstract

A composite crucible 10 is characterized in the use of mullite (3Al 2 O 3 .2SiO 2 ) as the basic material of the crucible. The composite crucible 10 has a crucible body 11 made of mullite material whose main component is alumina and silica, and a transparent vitreous silica layer 12 formed on the inner surface of the crucible body 11 . The thickness of the transparent vitreous silica layer 12 is smaller than that of the crucible body 11 . The crucible body 11 is formed by the slip casting method, and the transparent vitreous silica layer 12 is formed by the thermal spraying method.

1 . A method of manufacturing a composite crucible having a straight body portion and a bottom portion and used for supporting silicon melt, comprising a process of forming, by the slip casting method or the arc fusing method, a crucible body made of mullite material whose main component is alumina and silica, and a process of forming a transparent vitreous silica layer on an inner surface side of the crucible body. 
     
     
         2 . The method of  claim 1 , wherein the transparent vitreous silica layer is formed by the thermal spraying method. 
     
     
         3 . The method of  claim 2 , wherein, before the transparent vitreous silica layer is formed, an opaque vitreous silica layer containing numerous microbubbles is formed on the inner surface side of the crucible body by the thermal spraying method. 
     
     
         4 . The method of  claim 1 , wherein the transparent vitreous silica layer is formed by the arc fusing method. 
     
     
         5 . The method of  claim 4 , wherein the opaque vitreous silica layer containing numerous microbubbles is formed by the arc fusing method together with the transparent vitreous silica layer between the crucible body and the transparent vitreous silica layer. 
     
     
         6 . The method of  claim 1 , a vitreous silica molded body containing the transparent vitreous silica layer is inserted into the crucible body. 
     
     
         7 . The method of  claim 6 , wherein the vitreous silica molded body has two layer structure of the opaque vitreous silica layer on the outer surface side and the transparent vitreous silica layer on the inner surface side, and an opaque vitreous silica layer containing numerous microbubbles is formed between the crucible body and the transparent vitreous silica layer by inserting the vitreous silica molded body into the crucible body. 
     
     
         8 . A method of manufacturing a silicon crystal by contacting a seed crystal to silicon melt in the composite crucible, and gradually pulling the seed crystal to grow a silicon crystal, wherein the composite crucible has a straight body portion and a bottom portion, and has a crucible body made of mullite material whose main component is alumina and silica, and a transparent vitreous silica layer formed on an inner surface of the crucible body, and the thickness of the transparent vitreous silica layer is smaller than that of the crucible body.