Designing extreme-ultraviolet lithographic objective for 11 nm node

摘要

Extreme ultraviolet (EUV) lithography is one of the most promising technologies for 11 nm node. In this paper, a six-mirror objective system with a higher numerical aperture (NA) 0.5 and a central obscuration was designed with grouping design method. Some key issues about grouping design and control of obscuration were discussed in detail. Design result shows that the size of obscuration is smaller than 30% radius of the pupil and the composite Root-Mean-Square (RMS) wavefront error can reach 0.029 λ (λ=13.5 nm) in a 13 mm× 1 mm ring field. Design of this six-mirror objective system provides a potential solution for 11 nm node of EUV lithography.