Immersed nanospheres super-lithography for the fabrication of sub-70nm nanoholes with period below 700nm

A maskless nano-lithography method by using polystyrene spheres (PSs) self-assembled on silver slab (NSSL) was proposed in [optics express, Vol. 16, No. 19 (2008) 14397]. Following that, to break the limitations in resolution and PSs period of NSSL method, in this paper, we present PSs immersed super-resolution lithography (NSISL) technology by embedding the PSs into appropriate material to improve the efficiency of the surface plasmon excitation. The energy modulating mechanism and the rules of the resolution affected by silver slab were studied by calculating and analysing the energy distribution. The curve of the lithography resolution versus the silver thickness was presented. In order to verify this method, contrast analysis was carried out with NSSL. The results show that the lithography resolution is improved efficiently. Taking a specific configuration with PS diameter of 600nm as an example, the resolution was improved to 54nm from 190nm with Ag thickness of 25nm. Based on the calculation results, we carried out the experiments. Nano holes with dimension of 75nm and period of 600nm were obtained.