Influence of laser parameters and material properties on micro drilling with femtosecond laser pulses

We report experimental results of drilling micro holes in Al, Mo, Ti, Cu, A g, Au, and brass thin metal foils in air using 60-femtosecond Ti:sapphire l aser pulses. The influence of laser parameters and material properties on d rilling processes at the sub-10-micron scale has been examined. Comparison of hole drilling using 60-fs pulses with that using 50-ps and 10-ns pulses at an energy fluence of similar to 15 J/cm(2) indicates that a significant amount of melting is present in both ps and ns regimes, whereas with fs pul ses, fewer and much smaller droplets from the molten phase are observed.