Patent ID: 8715415
Filing Date: 2014-05-06
Classification: C30B,Y10T

Abstract:
1. A vitreous silica crucible having a sidewall part, a curved part and a bottom part, for pulling silicon single crystals, the vitreous silica crucible comprising: a transparent vitreous silica layer provided on an inner surface of the crucible; and an opaque vitreous silica layer provided on an outer surface of the crucible, and including a plurality of bubbles, wherein: a bubble content of the transparent vitreous silica layer is 0.1% or less and the opaque vitreous silica layer is higher in bubble content than the transparent vitreous silica layer, the opaque vitreous silica layer has a bubble diameter distribution in which the content of bubbles having a diameter of less than 40 is 10% or more and less than 30%, the content of bubbles having a diameter of 40 or more and less than 90 is 40% or more and less than 80%, and the content of bubbles having a diameter of 90 or more is 10% or more and less than 30%, the vitreous silica crucible is rotationally molded, and the rotational molding includes performing arc discharge after charging the quartz powder used as a raw material of the transparent vitreous silica layer in a rotating carbon mold, and further includes reducing a pressure in the mold so that a gas inside the quartz is sucked into the outer layer through an air passage formed in the mold and then discharged to the outside.