Patent ID: 6942934

Claim:
A glass substrate having uniform composition both at a surface and an interior thereof and having an amorphous structure, wherein the glass material fulfills the following conditions: ( A/B )× E× 10 7 ≧30 62×10 −7 ≦A≦ 82×10 −7 B≦ 250 ppb (per 2.5-inch disk) 85 ≦E≦ 95 where A represents a linear thermal expansion coefficient (/° C.); B represents alkali elution (ppb) (per 2.5-inch disk); and E represents a Young's modulus (GPa); wherein the glass substrate is produced by undergoing a polishing step and then a cleaning step in which the glass substrate is cleaned with at least one of a pure water liquid, an acidic liquid, and an alkaline liquid, and a surface roughness Ra after the polishing step and a surface roughness Ra′ after the cleaning step fulfill both of the following conditions: Ra′/Ra≦ 1.5, and Ra≦ 1.0 nm.