Influence of the confinement on laser-induced dry etching at the rear side of fused silica
- 232 Downloads
Laser-induced etching at the rear side of transparent material enables high-quality machining results. However, the mechanism is still not completely recognized which would allow further optimization. Therefore, multi-pulsed laser-induced backside dry etching with different thick photoresist films was studied experimentally for air (MP-LIBDE) and water confinements (cMP-LIBDE). The water confinement causes differences in photoresist ablation morphology and etching rate in dependence on laser fluence, film thickness and pulse number. Owing to the water confinement, the extent of photoresist film spallation and the etching rate slope difference in low and high fluence ranges are reduced. In particular, the etching rate of cMP-LIBDE keeps constant with different film thicknesses in contrast to MP-LIBDE. Two effects that are related to the water confinement, mechanical confinement and heat transfer alterations, are analysed and discussed in relation to the differences between MP-LIBDE and cMP-LIBDE.
KeywordsEtching Rate Laser Spot Laser Fluence Rear Side Pulse Number
The authors wish to acknowledge the help of Mrs E. Salamatin with the interference microscopic measurements and for careful reading of the manuscript and Mrs. I. Herold for supporting in preparation of the films. This work was financially supported in parts by the Deutsche Forschungsgemeinschaft, the European Union, and the European Social Fund through project Supercomputer, the national virtual lab (Grant no.: TAMOP-4.2.2.C-11/1/KONV-2012-0010) and the DAAD (no.: 56266271). Further, the Fundamental Research Funds for the Central Universities (No. 30915015104), the National Natural Science Foundation of China for Young Scholars (No. 11402120) and the Jiangsu Natural Science Foundation for Young Scholars (No. BK20140796) provide financial support.
- 11.K. Zimmer, M. Ehrhardt, R. Böhme, Laser ablation in liquids, in Principles and Applications in the Preparation of Nanomaterials, ed. by G. Yang (CRC Press, Boca Raton, 2012), p. 1032Google Scholar