SELECTIVE REMOVAL OF TRANSPARENT CONDUCTIVE OXIDE LAYERS WITH ULTRASHORT LASER PULSES: FRONT- VS. BACK-SIDE ABLATION

摘要

High average power, high repetition rate ultrashortrnpulse (pulse duration < 10 ps) laser systems with μJrnpulse energies [1, 2] are increasingly used for biomedicalrnand material processing applications.rnInteresting applications for the ultrashort pulse laserrnsystems are in the field of selective structuring of thinfilms.rnThin-film solar cells have shown a big potentialrnto decrease cost of manufacturing for photovoltaicrngeneration. Despite many research attempts tornoptimize materials the mass production of thin-filmrnsolar cells is still looking for versatile tools for thernstructuring of the thin-film coated area, where thinrnfilms with a thickness of ca. 1 μm have to be linernstructured with galvanic separation without damagingrnthe substrate or any other layers.rnIn this paper we report on recent results on thernselective ablation of transparent conductive oxidern(TCO) thin film, i.e. Boron-doped ZnO. The multipulsernprocess thresholds were determined for directrnand induced (lift off) laser-processing. Fromrncomparison of the process thresholds for both methodsrnwe can conclude that the induced ablation is morernsuitable for the structuring of the TCO layer. On thernother hand, structuring of the TCO layers by inducedrnablation is more complicated due to its strongrndependence on the quality of the glass substrate.