Proton beam fabrication of nickel stamps for nanoimprint lithography

Nickel stamps with micro and nano-scale relief features on their surfaces have been fabricated using proton beam writing coupled with nickel sulfamate electroplating. A focused beam of sub-micron 2.0 MeV protons was used to direct-write 3D patterns into spin coated PMMA resist, and a single step nickel sulfamate plating process has been used to produce metallic negatives from these patterns. The fabricated metallic stamps exhibit high aspect ratio surface patterns with smooth and vertical side-walls. Nano-indentation and atomic force microscopy (AFM) measurements of the features on the surface of the stamps indicate a hardness and side-wall roughness of 5 GPa and 7 nm respectively. Using nanoimprint lithography, the stamps fabricated using proton beam writing and electroplating have been successfully used to replicate patterns into PMMA.