GLASS SUBSTRATE WITH SMALL DENT AND PRODUCTION THEREOF

摘要

PURPOSE: To produce a glass substrate for a planer microlens having lots of small dents by subjecting a substrate with a mask film having lots of small apertures to dry etching, and to form small dents each having an arc cross section by specifying the surface roughness of the glass substrate before processing. CONSTITUTION: A quartz glass substrate 1 is ground with a cerium oxide powder under conditions of small load and low grinding speed. The surface roughness of the glass substrate 1 after ground is specified to <=0.4nm center line average roughness Ra. Then a three-layered film of CrOx/Cr/CrOx is formed by sputtering on the substrate surface. Then a pattern of small apertures which are two-dimensionally arranged is formed in a Cr film on the surface by using a photoresist, and then quartz glass substrate 1 having the apertures thus formed is chemically etched so that the surface of the glass substrate is etched from the apertures as the starting point of etching. Thus, small dents 3 having an arc cross section are formed.