Fabrication of ordered silicon nanopillars and nanowires by self-assembly and metal-assisted etching

Silicon nanowires (SiNWs) and nanopillars have been obtained by metal-assisted etching (MAE), starting from silver thin films deposited by thermal evaporation and sputtering on silicon substrates. Different deposition methods and thickness are strongly affecting spatial distribution and shapes of the extruded silicon nanostructures. The paper reports a study of distribution and morphology, as a function of silver thickness, deposition conditions and etching times. The application of polystyrene soft masks obtained by self-assembly and the sputter-etching by Ar ions allow the formation of regular indentations in the silver thin films, giving origin to a regular distribution of extruded pillars and wires during the following etching in HF:H2O2:H2O. The aqueous etching and the use of silver still influence the homogeneity of the etching result on large area and introduce a modulation in the etching front, so affecting thickness homogeneity. Work is in progress to replicate these former results with gold and different etching solutions.