Super-resolution in laser annealing and ablation

This letter reports observation of ablated holes as small as 0.7 mum fabricated by single 25 ns pulses of KrF (lambda = 248 nm) laser focused onto a 5.6 mum spot. Samples with high thermal conductivity films with respect to that of the substrate (Si/silica, Al/glass) repeatedly showed considerable reduction in the size of the ablated spot (0.7- and 1.2-mum-diam holes, respectively). This letter also presents a likely mechanism of the observed super-resolution and the criteria necessary to achieve super-resolution. Due-to the nonoptical origin of this effect it is expected that a tightly focused (<0.5 μm) laser beam can be used to ablate with nanoscale (<100 nm) resolution. (C) 2004 American Institute of Physics.