Complex nanostructures in PMMA made by a single process step using e-beam lithography

We present results on the single step fabrication of autocentered nanopillars with surrounding circular rim. This particular 3-dimensional shape is created by the energy density distribution of incident and backscattered electrons and reflects the dual behavior of PMMA as positive and negative e-beam resist. Structures with 80 nm rim diameter and 20 nm wide nanopillars could be realized. We could show that the characteristic dimensions of the structures can be varied almost independently by playing with the exposure parameters. Qualitative and quantitative analysis of the structure shapes are described and several fields of application are proposed.