Cross‐linked polymers for nanofabrication of high‐resolution zone plates in nickel and germanium

A high resolution cross‐linked PMMA resist has been synthesized and optimized for the generation of zone plate patterns down to 19 nm linewidth with e‐beam lithography. This resist shows an increased resolution compared to PMMA for generating periodic structures with a line to space ratio of 1:1. Furthermore, we developed a cross‐linked copolymer based on styrene and divinylbenzene, which is used in a new trilevel reactive ion etching (RIE) process. In this process a resist pattern of low aspect ratio can be transferred into a copolymer galvanoform with high aspect ratios for the electrodeposition of nickel. The copolymer has also been used as a highly selective etching mask for zone plate pattern transfer into germanium by RIE.