Etching of transparent materials by laser ablation of an organic solution

Abstract

Transparent materials such as fused silica and quartz crystal were etched upon irradiation of an organic solution containing pyrene, using a conventional KrF or XeCl excimer laser. Threshold fluence for etching was 240 mJ/cm(sup 2) for fused silica, which was remarkably low compared with that of direct ablation using conventional lasers. The etch rates depended on the concentration of pyrene. The mechanism is explained by cyclic multiphotonic absorption of pyrene in the excited states, thermal relaxation, and formation of superheated solution. As the results, the transparent material is etched in a heating process by a superheated liquid and an attacking process by a high temperature and pressure vapor.