Patent ID: 8328602

Claim:
A method for manufacturing a glass substrate for information recording medium, said method comprising: a lapping step of lapping a circular glass plate made of an alkali aluminosilicate glass; and a subsequent cerium oxide polishing step of polishing the circular glass plate with a slurry containing a cerium oxide abrasive, wherein a difference (SiO 2 −Al 2 O 3 ) obtained by subtracting an Al 2 O 3 content from an SiO 2 content in the alkali aluminosilicate glass is 62% by mole or less; and wherein said method further comprises: subsequently to the cerium oxide polishing step, a detergent rinsing step, and subsequently to the detergent rinsing step, a cleaning step of cleaning the circular glass plate with a cleaning liquid having a sulfuric acid concentration of 50% by mass or more and 80% by mass or less and a hydrogen peroxide concentration of 3% by mass or more and 10% by mass or less at a liquid temperature of 50° C. or higher and 100° C. or lower, and after the cleaning step, a finish polishing step of polishing a main surface of the circular glass plate with a slurry containing a colloidal silica abrasive.