Glass substrate and leveling thereof

摘要

A glass substrate having a surface which has been leveled, preferably to a flatness of 0.04-1.3 nm/cm<2 >of the surface, by local plasma etching is provided. A glass substrate whose surface carries microscopic peaks and valleys is leveled by measuring the height of peaks and valleys on the substrate surface, and plasma etching the substrate surface while controlling the amount of plasma etching in accordance with the height of peaks.