Surface microstructuring of transparent materials by laser-induced backside wet etching using excimer laser

Abstract

Silica glass is an important material in optics and optoelectronics because of its outstanding properties, such as transparence in a wide wavelength range, strong damage resistance for laser irradiation, and high chemical stability. In order to develop simpler processes of micro-fabricating silica glass using a pulsed laser, we have investigated a one-step method to microfabricate a silica glass plate using laser-induced backside wet etching (LIBWE) upon irradiation with a ns-pulsed excimer laser. Our idea of LIBWE is based on the deposition of laser energy on the surface of silica glass using ablation of a dye solution. When the dye solution was ablated upon the laser irradiation, the etching of a surface layer was performed on the silica glass. We have succeeded in the micro-fabrication of such transparent materials as silica glass, quartz, calcium fluoride, sapphire and fluorocarbon resin. The advantages of our LIBWE method are as follows, (i) a low laser fluence and constant etch rate, (ii) microfabrication without debris and cracks formation, (iii) large area irradiation with an excimer laser beam through a mask projection, (iv) simple pre-/post-treatment on target substrates. This is a one-step process simpler method at ambient pressure, which would be used for mass production.