Characterizing EMA modelled EUV absorbers for high reflectivity: high phase performance

Rajiv N. Sejpal; Bruce W. Smith

doi:10.1117/12.2617589

26 May 2022 Characterizing EMA modelled EUV absorbers for high reflectivity: high phase performance

Rajiv N. Sejpal, Bruce W. Smith

Proceedings Volume 12051, Optical and EUV Nanolithography XXXV; 120510E (2022) https://doi.org/10.1117/12.2617589
Event: SPIE Advanced Lithography + Patterning, 2022, San Jose, California, United States

Abstract

Attenuated phase shifting masks (attPSM) for EUV lithography have shown the potential to improve the aerial image contrast through light and phase modulation and reduced mask three-dimensional (M3D) effects through thinner absorber. However, a robust optical design capable of generating almost identical performance for various patterns and feature sizes needs to be determined. The ability to identify and experimentally verify various mask absorber candidates is both challenging and expensive. Effective media approximation (EMA) identified material candidates have been shown to simplify the determination of material candidates through known optical constants of the constituent elements. An approach to engineer the desired optical properties and experimentally verify EMA modeling technique through multilayer thin films is presented. Mo – Ni multilayer films satisfying EMA requirement are deposited through RF magnetron sputtering. The verification of optical constants for multilayer films with 20%, 50% and 90% Ni volume fractions is performed at visible wavelengths through UV-Vis-NearIR variable angle spectroscopic ellipsometry (VASE). EMA modeled multilayer absorber candidates are shown to have the flexibility in obtaining desired optical properties based on the layout-design requirements.

Citation Download Citation

Rajiv N. Sejpal and Bruce W. Smith "Characterizing EMA modelled EUV absorbers for high reflectivity: high phase performance", Proc. SPIE 12051, Optical and EUV Nanolithography XXXV, 120510E (26 May 2022); https://doi.org/10.1117/12.2617589

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