Patent ID: 9534318
Date: 2017-01-03
CPC Classifications: B41M,C03B,C03C,C30B,Y10T

Claim:
1. A method of manufacturing a vitreous silica crucible for pulling a silicon single crystal, comprising: a silica powder layer forming process of forming the silica powder layer by depositing silica powder on an inner surface of a mold defining an outer shape of the vitreous silica crucible; an arc heating process of fusing, by arc heating, the silica powder layer in the mold to form the vitreous silica crucible having a vitreous silica layer and terminating the arc heating so as to leave unfused silica powder layer between the vitreous silica layer and the mold; a taking-out process of taking out the vitreous silica crucible from the mold; a honing process of removing the unfused silica powder layer on the outer surface of the vitreous silica crucible; and further comprising, after the taking-out process and before the honing process, a marking process of marking by a laser beam an identifier comprised of multiple groove lines constituting alphabetic characters, numeric characters, or a bar code on the outer surface of the vitreous silica crucible to identify various kinds of crucibles, wherein each groove line after the honing process has a depth of 0.2 to 0.5 mm, and a width of 0.8 mm or more at the opening of the groove line, and each groove line has a cross-sectional shape of an inverse trapezoid; each groove line is formed by: (i) setting, on the outer surface of the vitreous silica crucible under the unfused silica powder layer, a focal point of the laser released from a laser marker; (ii) in that state, reciprocally moving the focal point along a longitudinal direction of the groove line at a width-direction position to form a part of the groove line; (iii) shifting the focal point in a width direction to a next width-direction position and repeating step (ii); and (iv) repeating step (iii) to form each of the multiple groove lines with the inverse trapezoid cross section, wherein a width of an opening in the unfused silica powder layer is wider than a width of an opening in the each of the multiple groove lines, and the number of the width-direction positions is 3 to 10 for the each groove line.