Chemical Etching Using KOH Aqueous Solution for Corona-Charge Micropatterning of Soda-Lime Glass

Abstract

The selectivity of chemical etching for a soda-lime glass substrate to which a micropatterned electric field is applied by corona-charging treatment was investigated. A grating pattern with a period of 4 µm was transferred in a soda-lime glass substrate via corona-charging treatment with a mask template. A diffraction efficiency of 0.02% was detected from the refractive index grating in a template-removed glass substrate. A surface relief grating with a period of 4 µm was fabricated on the glass substrate by selective etching using KOH aqueous solution. The etching rate of the corona-charge-treated domain of the glass substrate was 1.6 times higher than that of normal glass. An enhancement of the etching rate of the glass substrate by the corona-charging treatment occurred up to a depth of approximately 200 nm from the surface. After the surface structural change from the refractive index grating, diffraction efficiency increased to 1.64%, which was 80 times higher than that before chemical etching.