Laser-induced local dehydroxylation on surface-oxidized silicon substrates: mechanistic aspects and prospects in nanofabrication

Abstract

Processing of silicon oxide surfaces with a focused laser beam at a wavelength of 514 nm has been investigated. Laser processing of native silicon samples (dox=1–2 nm) allows the fabrication of reactive templates with laterally varying hydroxyl group density. Very similar results were also obtained on thermally oxidized silicon samples (dox≈100 nm), whereas respective experiments on quartz plates have failed. These results support a photothermal mechanism where laser irradiation causes a local temperature rise and initiates dehydroxylation. In agreement with a photothermally induced dehydroxylation reaction, a thermokinetic analysis of the experimental data points to a highly activated process. In conjunction with site-selective functionalization routines this opens up an avenue towards functional surface structures with lateral dimensions significantly below the optical diffraction limit.