Fabrication of free-standing subwavelength metal–insulator–metal gratings using high-aspect-ratio nanoimprint techniques

Abstract

In this paper, we report on the construction of a free-standing metal–insulator–metal (MIM) subwavelength grating by nanoimprint and lift-off techniques, which can be used as a plasmonic color filter for imaging a multicolor spectrum. The free-standing subwavelength grating was designed to be composed of Al (50 nm)–SiO2 (150 nm)–Al (50 nm) layers, and the thickness of the SiO2 layer determined the wavelength selectivity for the color filter. The residual-free nanoimprint with an aspect ratio of was applied in the lift-off process to the formation of MIM gratings. We successfully developed subwavelength MIM gratings with heights of more than 200 nm. We also demonstrated the fabrication of a free-standing MIM grating without lateral stiction, which was expected to improve the wavelength selectivity of a free-standing plasmonic color filter.