Nanoimprint Lithography Technique for the Planarized SU-8 Nanogratings Formation on Microstructured Surfaces

A technique for the thin planarized nanogratings formation from an SU-8 negative resist with an overlayer thickness up to 20 nm on the microstructured substrate surface is proposed in this work. The technique is based on the spincoating of a thin SU-8 layer on a microstructured surface and a subsequent thermoplastic planarization of the resist surface with a flat polymer stamp. At the final stage, ultraviolet nanoimprint lithography was performed using a nanostructured polymer stamp to form a nanograting on the SU-8 resist layer surface. The technique capabilities were demonstrated on the example of the formation of nanogratings with the periods of 180 and 90 nm with a controlled nanogrooves depth from 10 to 50 nm in a planarized SU-8 resist layer covering the substrate surface with microstructures. Such ultraviolet nanoimprint lithography conditions were found, and that makes it possible to reduce the formed nanograting period by 2 times, compared to the original master stamp.