GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM, MAGNETIC RECORDING MEDIUM, AND METHOD FOR MANUFACTURING GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM

摘要

This invention provides a glass substrate for an information recording medium, which has an improved chemical durability and, at the same time, is free from substrate deformation and a change in substrate properties. A glass substrate is chemically treated to form a chemical treatment layer on its surface. In this case, the chemical treatment is carried out so that a chemical treatment layer having a larger thickness is formed on the glass substrate in its part having a larger surface roughness before the chemical treatment. From the viewpoint of imparting a higher level of chemical durability, the thickness D of the chemical treatment layer preferably satisfies the following formula (1): 100Ra = D = 3000Ra (1) wherein Ra represents the surface roughness of the glass substrate before the chemical treatment.