Advancements in EUV photoresists for high-NA lithography

EUV resist materials play a vital role in enabling advanced lithographic technologies for high-volume manufacturing (HVM) targeting nodes below 5 nm. In this study, we report an extensive performance characterization of available EUV photoresists for future high-NA EUV lithography. We investigated the performance of various resists using the EUV interference lithography tool at the Swiss Light Source (SLS) within the framework of a collaboration between the Paul Scherrer Institute and ASML. This paper highlights the major improvements we observed in 2023 and presents the best performing resists of 6 different vendors for half-pitch (HP) 14 and below. Important performance characteristics considered in this study are resolution or HP, dose-to-size (DtS) and line-width roughness (LWR). To evaluate the overall performance of the resists, we used the Z-factor. We investigated both chemically amplified resists (CAR) and non-CAR materials. CARs from two vendors achieved a resolution down to 11 nm half-pitch, while multitrigger resists (MTR) reached a resolution of 13 nm. A new metal organic resist (MOR) achieved a resolution down to 11 nm. MTR and one CAR material achieved the lowest Z-factor to date. In addition, we investigated the effect of underlayers on the performance of MOR and compared the performance of the new MOR to the predecessor. We, finally, discuss the overall progress in resist performance over the recent years. We observed a steady improvement across several resist platforms, which is encouraging for global EUV resist development towards high-NA EUVL.