Control of deposition channels in nanosphere templates for high-density nanodot array production

The deformation of 'soft' polystyrene spheres is found to limit the usefulness of nanosphere lithography in high-density applications because of the eventual closure of the void areas between the self-assembled nanospheres which function as channels for material deposition. We have used a plasma etching technique to reopen and enlarge these channels in the template in a controlled manner. This enables the controlled fabrication of a range of nanoarrays of very high density and variable sizes. The resulting shape of the nanodots produced can be understood by considering the etching-induced surface diffusion of the polystyrene in the plasma treatment.