Genetic optimization of aperiodic multilayer masks for high and hyper-NA EUV lithography

W. Ethan Maguire; Bruce W. Smith

doi:10.1117/12.3010983

10 April 2024 Genetic optimization of aperiodic multilayer masks for high and hyper-NA EUV lithography

W. Ethan Maguire, Bruce W. Smith

Author Affiliations +

Proceedings Volume 12953, Optical and EUV Nanolithography XXXVII; 129531A (2024) https://doi.org/10.1117/12.3010983
Event: SPIE Advanced Lithography + Patterning, 2024, San Jose, California, United States

Conference Poster

Abstract

To achieve higher resolution extreme ultraviolet lithography targeted toward sub10nm, reflective projection scanner image numerical apertures (NA_i) are being increased beyond the current value of 0.33 to 0.55, and upwards of 0.75 as a desirable target. Bragg reflectors using alternating silicon and molybdenum that have heretofore been coated as periodic multilayers cannot achieve desired reflected amplitudes as corresponding 0.25X mask numerical apertures (NA_m) are accordingly increased. Additionally, TM polarized image modulation decreases with NA, which becomes significant at 0.55 and above. We present here the optimization of non-regular alternating, or aperiodic, silicon-molybdenum multilayer reflective coatings that can achieve improved amplitude and polarization performance through angle as higher-NA EUVL lithography is pursued. Through the use of rigorous EM computation paired with a genetic optimization method, we show that amplitude apodization can be recovered to 60% peak reflectance for NA_m values up to 0.2 (corresponding to NA_i values of 0.8), while at the same time achieve a TE degree of polarization (DOP) exceeding 40%.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

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W. Ethan Maguire and Bruce W. Smith "Genetic optimization of aperiodic multilayer masks for high and hyper-NA EUV lithography", Proc. SPIE 12953, Optical and EUV Nanolithography XXXVII, 129531A (10 April 2024); https://doi.org/10.1117/12.3010983

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