Three-dimensional patterning technique for nanoimprint mold by dwell-time algorithms with iterative blind deconvolution method

Nano- and micropatterned surfaces attract considerable research attention because they can be used in various applications such as plasmonic nanostructure. In particular, three-dimensional (3D) surfaces such as periodic structures on devices have been widely studied. Therefore, a high-throughput patterning technique that enables the use of such complex 3D surfaces in industrial applications are needed. Nanoimprint lithography (NIL) is a promising technology that represents a major breakthrough for this purpose because it is a simple patterning technique. However, the NIL process includes a direct contact process; a 3D master mold is therefore required to produce complex 3D surfaces using NIL. Electron beam lithography (EBL) is widely used to fabricate master molds for NIL applications, but obtaining a smooth 3D mold with a sub-500 nm step pattern directly is difficult with conventional EB dose modulation methods. In this study, we propose a fabrication method of NIL molds using dwell-time algorithm to obtain a smooth surface using direct 3D patterning based on EBL. Consequently, we obtained a target distribution of a 3D pattern with a two-step structure for EBL.