Patent ID: 9157168
Filing Date: 2015-10-13
Classification: C03B,C30B,Y10T

Abstract:
1. A vitreous silica crucible for pulling a silicon single crystal, wherein the crucible has a wall comprising, from an inner surface toward an outer surface of the crucible, a transparent vitreous silica layer having a bubble content rate of less than 0.5% and having an OH group concentration of 30 ppm or less, a first bubble-containing vitreous silica layer having a bubble content rate of 1% or more and less than 50%, a semi-transparent vitreous silica layer having a bubble content rate of 0.5% or more and less than 1.0% and having an OH group concentration of 35 ppm or more and less than 300 ppm, and a second bubble-containing vitreous silica layer having a bubble content rate of 1% or more and less than 50%; wherein the first bubble-containing vitreous silica layer comprises an impurity-containing vitreous silica layer to which impurities are added acting as nuclei when turning the vitreous silica into crystalline silica in a high temperature environment, wherein a concentration of impurities in the impurity-containing vitreous silica layer is 20 ppm or higher and is higher than that in the neighboring layers, and wherein the total thickness of the first and second bubble-containing vitreous silica layers is 50% or less of the thickness of the wall.