Lithography for sub-60 nm resist nanostructures

As the semiconductor community continues to follow the SIA Roadmap, resist structures are being printed further into the nanometer domain. However, a persistent issue for successful sub-60 nm resist patterning is mechanical stability at high aspect ratios. The objective of this paper is to understand what processing conditions facilitate processing resist nanostructures with useful aspect ratio for the fabrication of sub-60 nm transistors. We have found that, in aqueous based development and rinse, if the resist thickness is reduced then the aspect ratio is sacrificed for the sake of resolution. The implication is that there is a resolution limit at which resist structures will have aspect ratios useful for device fabrication. We have also found that there are development effects that occur in the thick film regime not reproducible with thin films.