Enhanced Resolution of Poly-(Methyl Methacrylate) Electron Resist by   Thermal Processing
  Granular nanostructure of electron beam resist had limited the ultimate resolution of electron beam lithography. We report a thermal process to achieve a uniform and homogeneous amorphous thin film of poly methyl methacrylate electron resist. This thermal process consists of a short time-high temperature backing process in addition to precisely optimized development process conditions. Using this novel process, we patterned arrays of holes in a metal film with diameter smaller than 5nm. In addition, line edge roughness and surface roughness of the resist reduced to 1nm and 100pm respectively. 
Nima Arjmandi, Liesbet Lagae, Gustaaf Borghs
cond-mat.mtrl-sci