F2-laser modification and patterning of silicone films

Pulsed laser irradiation of 3 μm thick silicone films at 157 nm below and above the ablation threshold of about 100 mJ/cm2 has been investigated. Significantly above the ablation threshold, clean material removal is observed. Irradiation below threshold leads to surface swelling and a modification of the chemical composition as revealed by Raman spectroscopy. After 10,000 pulses at 30 mJ/cm2 a nearly carbon free silica like material is obtained. The 157 nm-ablation threshold of this modified material amounts to 800 mJ/cm2, which is similar to that of fused silica. At 60 mJ/cm2, the CH3-content is similarly reduced, but a graphitization is observed after about 10 000 pulses. In both cases the modified material exhibits broadband visible luminescence. Combinations of modification and ablation are used to fabricate patterned silica films.