Ultra-thin film photoresist characterization for high resolution in Extreme Ultraviolet Lithography

A major challenge for photoresist technology will be to develop a resist system that is able to resolve ever shrinking feature sizes down to 8 nm for high-NA extreme ultraviolet (EUV) lithography by year 2024, within specifications of resolution, line edge roughness and sensitivity. This requires quantifying parameters that influence EUV based resist patterning performance on the level of inherent resist properties. Building knowledge on this subject will increase the fundamental understanding of ultra-thin film photoresist interactions and aid towards a more guided resist development for future (high-NA) EUV lithography processes. 

The main objective is to gain understanding on how reduction of resist volume, down to ultra-thin films (10 – 35 nm) for future high-NA EUV lithography, affects resist patterning performance. Challenges associated with this may be solved by extending the use of conventional CAR based resists, however the limited volume brings other parameters than acid diffusion into perspective (e.g. resist/substrate interactions). To elucidate the processes in the resist volume, characterization methodology with sensitivity at the nm3 level needs to be assessed. Moreover, with the move towards high-NA EUV the likelihood of shift from CAR to NCAR type resists increases. Since these resists rely on different light–matter interactions to come to development also this class of materials will be investigated to meet the specifications of N3.