Patent ID: 7732101

Claim:
A method of producing a glass substrate for a mask blank, in which a surface of the glass substrate is polished by the use of a polishing liquid containing abrasive grains, wherein: the polishing liquid comprises colloidal silica abrasive grains, the polishing liquid is alkaline, a content of the alkali metal in the colloidal silica abrasive grains is 0.1 ppm or less, the glass substrate is one of a glass substrate for a phase shift mask blank to be exposed by an ArF excimer laser, a glass substrate for a phase shift mask blank to be exposed by an F 2 excimer laser, and a glass substrate for a EUV reflective mask blank, and the surface of the glass substrate is polished so as to have a surface roughness required in an exposure wavelength to be used so that a height of a protrusion generated on the surface of the glass substrate during polishing falls within a phase defect range that is allowable for the exposure wavelength.