Large Area Silica Nano Grids by Homogeneous High Resolution Laser Patterning of SiOx-Films

Structured excimer laser back side irradiation of thin SiO x -films on fused silica substrates is used for the formation of complex micro-and nano-patterns. A polymeric superstrate serving as a confinement layer on top of the SiO x -film allows the formation of very smooth and regular patterns. Depending on laser processing parameters, either arrays of blisters or cups, or grids with free standing wires below 100 nm in diameter can be fabricated. To obtain these nano-features with high structure resolution on a comparatively large area with a single KrF-laser pulse (wavelength 248 nm), an optical system combining a beam homogenizer with a high resolution mask imaging optical system has been established. At fluences in the range of 300 to 400 mJ/cm very regular grid patterns with wires detached from the substrate and nodes attached to the substrate are obtained. The free standing wires have diameters down to less than 100 nm. The patterned SiO x -material can be oxidized to SiO 2 by thermal or laser treatment.