ABSTRACT
Material processing with pulsed lasers has been an intensive research topic since the invention of the laser in 1960. Nowadays, the laser is used as an efficient and qualified tool in many industrial processes such as heavy industrial cutting, hardening, and welding. In the microfabrication industry, however, the laser has not yet become a universal instrument. In general, one needs a special laser for a particular microstructuring application. Excimer lasers are used, for example, for the micromachining of ceramics and polymers, and Nd:YAG-lasers are used for microdrilling and marking. Moreover, for several applications, particularly for the precise microstructuring of metallic materials, the use of lasers with pulse durations in the range of nanoseconds to microseconds is limited due to thermal or mechanical damage (melting, formation of burr and cracks, changes in the morphology, etc.).These limitations have stimulated widespread research activities to minimize collateral damage and thermal diffusion out of the irradiated area by using ultrashort laser pulses, including investigations on the ablation of dielectrics (e.g., Küper and Stuke, 1989; Du et al., 1994; Pronko et al., 1995a; Stuart et al., 1995, 1996; Varel et al., 1996; Ashkenasi et al., 1998; Lenzner et al., 1998; von der Linde and Sokolowski-Tinten, 2000) and metals (e.g., Preuss et al., 1995; Krüger and Kautek, 1995; Momma et al., 1996; Nolte et al., 1997; Feuerhake et al., 1998; Wellershoff et al., 1999) as well as attempts to produce submicrometer structures (Pronko et al., 1995b; Simon and Ihlemann, 1996).
