Vitreous silica crucible for pulling single-crystal silicon and method of manufacturing the same
In order to provide a vitreous silica crucible which does not employ a crystallization accelerator but is difficult to deform during its use even under high temperature, and is easily manufactured, there is provided a vitreous silica crucible for pulling single-crystal silicon wherein the outer surface layer is formed of a bubble-containing vitreous silica layer, the inner surface layer is formed of a vitreous silica layer whose bubbles are invisible to the naked eye, a surface of the outer surface layer includes an unmelted or half-melted silica layer (abbreviated as a half-melted silica layer), and the center line average roughness (Ra) of the half-melted silica layer is 50 to 200 μm, also preferably, and the thickness of the half-melted silica layer is 0.5 to 2.0 mm.
1. A vitreous silica crucible for pulling single-crystal silicon comprising:
an outer surface layer which is formed of a bubble-containing vitreous silica layer, and an inner surface layer which is formed of a transparent vitreous silica layer, wherein:
a half-melted vitreous silica layer is on the outer surface in a straight body portion of the crucible, and a center line average roughness (Ra) of a surface of the half-melted vitreous silica layer is 180 to 200 μm;
a layer thickness of the half-melted vitreous silica layer is 1.5 to 2.0 mm; and
a layer thickness of the crystallization layer after pulling the single-crystal silicon is 0.6 to 2.2 mm.
2. A method of manufacturing a vitreous silica crucible in accordance with a rotary mold method, comprising the steps of:
heating the vitreous silica powder which is accumulated on the inner surface of a rotary mold, from a space side of the mold;
forming a glass crucible by vitrification;
taking the glass crucible out of the mold after cooling; and
subjecting the half-melted vitreous silica powder composed of unmelted or melted vitreous silica powder to a honing process in order for the center line average roughness (Ra) of the half-melted vitreous silica layer of the outer surface in a straight body portion of the crucible to be 180 to 200 μm, the layer thickness of the half-melted vitreous silica layer to be 1.5 to 2.0 mm, and a layer thickness of the crystallization layer after pulling the single-crystal silicon to be 0.6 to 2.2 mm.