METHOD FOR MANUFACTURING GLASS SUBSTRATE FOR HDD

PROBLEM TO BE SOLVED: To provide a method for manufacturing a glass substrate for an HDD with superior strength and high smoothness.SOLUTION: A method for manufacturing a glass substrate for an HDD includes at least two chemical strengthening processes for causing a glass substrate precursor having a center hole to have contact with a chemical strengthening liquid and substituting an alkali metal ion on a surface of the glass substrate with an alkali metal ion having a larger ion size than the alkali metal ion included in the chemical strengthening liquid so as to apply a compression stress layer. The method further includes a main surface treatment process carried out between the first chemical strengthening process and the second or later chemical strengthening process. In the method for manufacturing the glass substrate for the HDD, it is preferable that inner diameter polishing of the glass substrate precursor is carried out before the first chemical strengthening process, and that outer diameter polishing of the glass substrate precursor is carried out between the first chemical strengthening process and the second chemical strengthening process.