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

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.

Citation Download Citation

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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