Fabrication of subwavelength aluminum wire grating using nanoimprint lithography and reactive ion etching

We have demonstrated subwavelength aluminum (Al) gratings with a period of 200 nm using nanoimprint lithography (NIL) and reactive ion etching (RIE). Al dry etching was attempted using the etch mask formed by NIL. The SiO2 stamp with a size of 5 × 5 cm2 was fabricated using laser interference lithography and RIE. The NIL process was optimized on Al/glass substrate and various imprint resists were tested for the Al etching. We could obtain a vertical etching profile and an etch selectivity of 2 with mrI-8020 imprint resist. The Al RIE combined with NIL will be useful for the realization of subwavelength Al gratings with a high aspect ratio.