Ultrashort pulse laser patterning of indium tin oxide thin films on glass by uniform diffractive beam patterns
In the last decade, indium tin oxide (ITO) has been most commonly employed to create transparent conducting oxides (TCOs) thin films for many industrial applications. It is usually necessary to pattern ITO thin films to create functional structures for specific applications. Direct-write micro-patterning of ITO thin films by ultra-short pulse lasers has demonstrated high quality without requiring multiple processing stations, compared with conventional patterning technologies (e.g. wet-etch lithography). However, the processing efficiency and throughput with a single beam can be insufficient because of the high level of attenuation needed for the output to meet the required ‘thermal-free' parameters. In this paper, high throughput surface direct micro-structuring of ITO on glass is demonstrated by parallel processing using diffractive multiple ultrashort pulse laser beams (λ = 1064 nm, τp = 10 ps). By avoiding periodic and symmetrical geometry design, the diffractive multiple beam pattern generated by a spatial light modulator has high uniformity (the energy variation between each diffractive beam is <9%). The ITO thin film is removed by laser ablation of 25 identical beams at the same time without any damage to the glass substrate. Additionally, by synchronizing a scanning galvanometer, the processing demonstrates high flexibility to generate various surface patterns.