Laser writing of a subwavelength structure on silicon (100) surfaces with particle-enhanced optical irradiation

Spherical 0.5-μm silica particles were placed on a silicon (100) substrate. After laser illumination with a 248-nm KrF excimer laser, hillocks with size of about 100 nm were obtained at the original position of the particles. The mechanism of the formation of the subwavelength structure pattern was investigated and found to be the near-field optical resonance effect induced by particles on the surface. Theoretically calculated near-field light intensity distribution was presented, which was in agreement with the experimental result. The method of particle-enhanced laser irradiation has potential applications in nanolithography.