Patent ID: 7010939

Claim:
A method for polishing a surface of a glass substrate for a data recording medium, the method including a rough polishing step, a precision polishing step, and a super precision polishing step, the super precision polishing step comprising: a first polishing step for polishing the surface of the glass substrate with a first suspension, wherein the first suspension contains particles and a dispersion medium in which the particles are dispersed, wherein the main ingredient of the particles is silicon dioxide (SiO 2 ), and the average size (D 50 ) of the particles is equal to or less than 100 nm, and wherein the dispersion medium comprises an acid solution the pH of which is equal to or less than 4; and a second polishing step for continuously polishing the surface of the glass substrate with a second suspension, wherein the second suspension contains particles and a dispersion medium in which the particles are dispersed, wherein the main ingredient of the particles is silicon dioxide (SiO 2 ), and the average size (D50) of the particles is equal to or less than 100 nm, and wherein the dispersion medium comprises an alkaline solution the pH of which is equal to or more than 8.5.