Laser etching of indium tin oxide thin films by ultra-short pulsed laser

We have investigated laser etching that removed ITO (Indium Tin Oxide) thin films deposited on glass substrate directly and selectively by laser beam in dry process. At first, in order to examine the dependence of laser wavelengths at ablation, the first, second, third and fourth harmonic of nanosecond pulsed Nd:YLF laser were employed respectively As a result, comparatively good etching was performed by the UV wavelength. In the fine patterning of ITO, however, molten materials were observed around the edge of the pattern. Moreover, a few micro cracks occurred in the molten domain. In this research, therefore, we carried out laser etching by ultra-short pulsed laser (wavelength: lambda = 800 nm, pulse duration: 30 fs) to solve these heat influence problems. The line patterning of ITO (film thickness: 330 nm) was performed by control of laser fluence at fixed laser power and feed rate. In conclusion, we achieved good laser etching that the molten materials and the micro cracks were reduced and there were little debris near the groove, even processing in the atmosphere. Additionally, the removal of ITO was more efficiency as compared with nanosecond-laser so that effects of plasma shielding were lower at ablation.