Self Aligned Concentric Nanostructures Formed by E-beam Overexposure of PMMA and Single Post Processing Steps
We demonstrate the ability to control the creation of self aligned nanostructures by e-beam lithography, where a central nanopillar with circular rim is created in a single e-beam exposure [1,2]. This characteristic shape is formed by the energy density distribution of incident, forwardscattered and backscattered electrons  and reflects the dual behavior of PMMA as positive and negative e-beam resist. In addition, the high energy incident electrons have a confined heating effect on the PMMA and carbonize the polymer from top to bottom. At the same time, electrons backscattered from the underlying material will break the polymeric bonds around thiscarbonized region and render the PMMA soluble in developer solution.
Record created on 2011-08-23, modified on 2016-08-09