Liquid transfer imprint lithography: A new route to residual layer thickness control

Abstract

In this study, an extension of the soft UV nanoimprint process is presented with improved control of the residual layer thickness and significant reduction of the nanoimprint proximity effect. The process is based on the consecutive halving of the liquid resist layer by a liquid transfer process. In the initial stage, this liquid transfer process uses a thick initial resist layer to ensure complete filling of the stamp cavities. The thick residual layer is then thinned down to about half by peeling off the applied imprint stamp, a process that can be repeated until the desired residual layer thickness is achieved. The information carrying layer remaining on the stamp can be transferred conformally to any substrate even with nonplanar surfaces. The fabrication of silicon photonic waveguides and photovoltaic antireflection textures are two applications where the advantage of this process becomes particularly clear.