Photolithographic patterning at sub-micrometer scale using a three-dimensional soft photo-mask with application on localized surface plasma resonance

This paper presents a new method for fabricating arrayed metallic nano-structures with sub-micrometer line-widths over large patterning area sizes. It utilizes a soft mold containing arrayed surface micro-pyramids. A carbon-black photo-resist (PR) coating method is developed which can convert the soft mold into a photo-mask. This three-dimensional photo-mask is then applied for photolithographic ultraviolet (UV) patterning. In conjunction with standard metal lift-off process, arrayed metallic nano-structures are formed on glass substrates. A finite element simulation software is used to analyze the underlying mechanism of UV patterning using this new type of 3D photo-mask. The localized surface plasma resonance (LSPR) effects of the fabricated nano-structures are investigated both experimentally and theoretically. Good agreements are observed.