Excimer laser ablation removal of thin chromium films from glass substrates

The excimer laser has been widely used for the removal of thin metal films. In this work, excimer laser ablation was applied to remove chromium films from glass substrates. To understand the removal mechanism and to seek the optimal processing conditions for pattern generation, a one-dimensional hea t flow model was formulated which incorporated melting and vaporization. Mo rphological investigations were carried out experimentally on samples havin g different chromium film thicknesses that were irradiated with a KrF excim er laser. The thresholds for film damage, complete removal and glass damage were determined experimentally and compared with the calculated results. T he measured single-shot ablation rate is about twice as high as the numeric al predictions based on a heat conduction theory. The removal mechanism of the chromium film is found to be divided into two steps of pure vaporizatio n and melt expulsion by vapor recoil pressure. Optimal processing condition s were determined to enhance the accuracy and quality of film removal for p attern generation. Finally, the slit disk of a rotary encoder was manufactu red using the optimal processing conditions established. (C) 1999 Elsevier Science S.A. All rights reserved.