Product Code: ICAL07_M105

Selective Femtosecond Laser Micro-structuring of Photoresists and TCO
Authors:
Sandra Zoppel, Vorarlberg University of Applied Sciences; Dornbirn Austria
Stefan Partel, Vorarlberg Univ. of Applied Sciences; Dornbirn Austria
Georg A. Reider, Vienna Univ. of Technology; Vienn Austria
Max Lederer, HighQ Laser; Hohenems Austria
Pavlina Choleva, Vorarlberg Univ. of Applied Sciences; Dornbirn Austria
Presented at ICALEO 2007

We present recent results on selective laser ablation of thick photoresists (AZ-types) and TCO (transparent conductive oxide) layers from dielectric substrates. The well defined threshold for the ablation with ultrashort laser pulses provides, for many technologically important coating-substrate combinations, a process parameter window where one layer is selectively removed from the underlying substrate without affecting the substrate. By employing 300 fs-pulses with a pulse energy between 15 and 30 µJ (HighQLaser), we were able to selectively structure thick photoresist layers on a glass wafer with high accuracy and excellent edge definition. Subsequent sputter and micro-electroplating steps permit the fabrication of micrometer metallic structures that can serve, among other purposes, as an embossing tool or as a template for micro injection molding. We also demonstrate the potential of the selective ablation scheme for structuring TCO (ZnO, SnO2) layers on glass; again, ultrafast laser ablation permits high quality micrometer structuring almost free of any heat load to the material. With a relatively high process speed of 0.1 m/s, this technique could become an important process step in the production of thin film solar cells.