Composite crucible, method of manufacturing the same, and method of manufacturing silicon crystal
The purpose of the present invention is to provide a crucible which has high viscosity at high temperature, and can be used for a long time, and can be manufactured at low cost, and a method of manufacturing the same. The 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 the 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 can be formed by the slip casting method, and the transparent vitreous silica layer 12 can be formed by the thermal spraying method.
1. A composite crucible for supporting silicon melt and having a straight body portion and a bottom portion, comprising:
a mullite material layer comprising mullite material whose main component is alumina and silica, said mullite material comprising mullite in an amount of at least 50%;
a transparent vitreous silica layer formed on an inner surface side of the mullite material layer; and
an opaque vitreous silica layer containing numerous microbubbles and provided between and in contact with the mullite material layer and the transparent vitreous silica layer;
wherein the thickness of the mullite material layer is between 5 mm and 20 mm, the thickness of the transparent vitreous silica layer is between 0.5 mm and 2 mm, and
wherein the thickness of the opaque vitreous silica layer is the same as or smaller than that of the transparent vitreous silica layer.
2. The composite crucible of claim 1 , wherein an aluminium concentration in the mullite material layer is lowering from an outer surface side to an inner surface side of the mullite material layer.