Microstructuring and surface modification by excimer laser machining under thin liquid films

A novel technique for microstructuring various materials with excimer laser radiation is presented. A thin film of water is deposited on the surface during excimer laser machining. This method leads to some important advantages compared to the conventional dry excimer laser processing. The redeposition of ablated material is completely avoided resulting in a better quality of the microstructures. A subsequent removal of debris is not necessary. Melting of the irradiated material is reduced by applying a thin water film to the surface. Even microstructuring of metals by excimer laser radiation - up to now a problem due to the formation of a strong melting phase - becomes possible. For some ceramic materials (Al2O3) the ablation rate is increased significantly. Experiments were carried out with KrF and XeCl excimer lasers. The investigated materials were ceramics (Al2O3, Si3N4, SiC), glass, metals (stainless steel) and polymers. The ablation rate and quality of the microstructures was examined as a function of the processing parameters. The influence of the water film during the excimer laser ablation on the four-point bending strength of Al2O3 and Si3N4 was investigated.