Characterization of super-resolution photolithography

A pupil filtering lens system for improving depth of focus and resolution is introduced. The effectiveness of the pupil filtering lens system, which uses the Super-FLEX filter for window patterns and a high spatial frequency enhancing filter for periodical patterns, is discussed. Using these filters, it is possible to achieve 0.2-0.3 mu m patterns without phase-shift masks. The depth of focus and the practical resolution are compared for various super-resolution optical lithography methods. Preliminary experimental results from the pupil filtering lens were obtained, and the effect of the super-FLEX filter is confirmed.<>