Patent ID: 8585463

Claim:
A process for producing a glass substrate for an information-recording medium having a chemically reinforced layer formed with a chemical reinforcing liquid on a surface of a disk-shaped glass plate containing 0.01% by mass to 2% by mass of cerium oxide, the glass substrate being configured to have TIR of 0.7 μm or less per cycle in a circumferential direction at a position 0.75×r1 distant from the center of the glass plate, when r1 is a radius of an outer perimeter of the glass plate, by polishing of the surface in a step of rough polishing and a step of fine polishing, wherein the glass plate is roughly polished with a polishing agent containing cerium oxide as a main component in the rough polishing step, the glass plate after rough polishing is finely polished with a polishing agent containing colloidal silica grains in the fine polishing step, a stock removal in the fine polishing step is 0.2 μm to 2 μm, when a is the volume (liter) of a slurry containing the polishing agent used in the fine polishing step; b is the number of glass plates to be polished; X is the content (% by mass) of cerium oxide of the glass plates; Y is the stock removal (μm); and Z=Y ×area of substrate(cm 2 )×density of substrate(g/cm 3 ) (1), the polishing in the fine polishing step is carried out so as to satisfy ( X×Z )× b/a< 3(μg/liter) (2), and the glass plate after the rough polishing step is cleaned before the fine polishing step so as to adjust the amount of cerium oxide on the surface of the glass plate to be 0.125 ng/cm 2 or less.