Nanobump arrays fabricated by laser irradiation of polystyrene particle layers on silicon

Two-dimensional (2D) nanobump arrays were fabricated by laser irradiation of a regular lattice of absorptive polystyrene (PS) microspheres on an undoped (100) Si wafer. The experiments were performed with single-pulse 248 nm KrF laser radiation. The structure of the arrays fabricated by this method was characterized by field emission scanning electron microscope and atomic force microscope. The near-field effects under the absorptive particle are studied. The ablation and thermal processes induced by the optical near-field around the particles are investigated. The formation mechanism of nanobumps is discussed.