Parameter optimization in femtosecond pulsed laser etching of fluorine-doped tin oxide films

Abstract

In this study, the fluorine-doped tin oxide (FTO) film on a glass substrate was etched by using a femtosecond pulsed laser with a wavelength of 1030 nm, a repetition rate of 1 MHz and a pulse duration of 262 fs. The effect of laser fluence and scanning speed on the quality of the groove etched on the FTO film surface was systematically studied, trying to improve the groove quality. The results indicated that in order to obtain high quality grooves for use on touch screens, a balance needed to be achieved between laser fluence and scanning speed. Excessive laser fluence caused cracks at the bottom of the groove with shoulder protrusions formed at the edge of the groove, and the scanning speed had a considerable influence on the groove width at the same time. After discussing and comparing the results of five groups of experiments, the best groove quality was determined at the scanning speed of 3000 mm/s and the laser fluence of 1.1 J/cm2. In this case, the edge of the groove was sharp without obvious cracks and shoulder-like protrusions, and the groove width was 7.92 μm, which made it possible to process small etched areas for touch screen. Furthermore, the optimal parameters were confirmed to be available for processing a pattern on the touch screen sensor layer with a line spacing of 5 μm.