Formation of microbumps and protrusions on metal thin films by localized laser irradiation

We present results on the formation of microbumps, and high-aspect-ratio nano-scale protrusions on metal films as a result of single-pulse localized laser irradiation. A Q-switched nanosecond-pulse Nd:YAG laser, emitting at its fourth harmonic of 266 nm, was employed. Gold or platinum films with thicknesses of several hundred nanometers were irradiated in ambient or under low-vacuum conditions, with circular laser spots, several micrometers in diameter. A mask projection technique was used to generate these spot patterns. The resulting structures were examined by scanning electron microscopy. The formation mechanism of these structures is briefly discussed.