Fabrication of a three-dimensional nanoimprint mold by using electron beam lithography with consideration of the proximity effect

Abstract. Nanoimprint lithography (NIL) is a promising method for fabricating nanoscale patterns, because of its low cost and process simplicity. There is a growing demand for three-dimensional (3D) nanoimprint molds for various optical devices and dual-damascene processes. We examined the fabrication of a 3D line-and-space (L&S) pattern as a nanoimprint mold by low-acceleration-voltage (<5 kV) electron-beam (EB) lithography. Normally, it is difficult to obtain a fine L&S pattern by using a low acceleration voltage because of the large proximity effect caused by forward scattering of electrons. We therefore used an inorganic resist, which has higher contrast than an organic resist because of the smaller size of its molecules. As a result, a fine L&S patterned 3D nanoimprint mold with a line-width of less than 100 nm was fabricated by means of low-acceleration voltage EB lithography using an optimized EB dose and an optimized L&S pattern with an inorganic resist.