Alternative EUV mask with platinum-tungsten alloy for high-NA EUV lithography

Yunsoo Kim; Dongmin Jeong; Minsun Cho; Jinho Ahn

doi:10.1117/12.2641805

31 October 2022 Alternative EUV mask with platinum-tungsten alloy for high-NA EUV lithography

Yunsoo Kim, Dongmin Jeong, Minsun Cho, Jinho Ahn

Proceedings Volume PC12292, International Conference on Extreme Ultraviolet Lithography 2022; PC122920U (2022) https://doi.org/10.1117/12.2641805
Event: SPIE Photomask Technology + EUV Lithography, 2022, Monterey, California, United States

Conference Poster

Abstract

Extreme Ultraviolet Lithography (EUVL) is in high volume manufacturing (HVM) for the 7nm node, and a high-NA system for future 3nm nodes is currently in development. However, current Ta-based EUV masks have limited imaging performance due to mask 3D effects, so there is an urgent need for new advanced EUV masks. In this study, we propose a platinum tungsten (Pt-W) alloy as an alternative absorber material with advantages in both imaging performance and EUV mask manufacturing process. Since Pt is a material with both a low refractive index for phase shift effect and a high extinction coefficient for high absorption of EUV light, it shows improvement in imaging performance and mitigation of mask 3D effect (M3D). In order to improve the difficult etching properties of Pt, W was introduced as an alloy material, and a fluorine-based gas was selected as the etching gas. Through the PROLITH 2020b simulation tool, we found that the Pt-W alloy exhibits higher NILS and mitigates non-telecentricity compared to Ta-based absorbers. We also evaluated the etching properties of Pt-W alloy thin films using CF4/Ar gas. As a result, it was confirmed that the etch rate of PtW was about 1.86 times higher than that of Pt, and a platinum tungsten alloy pattern having a high sidewall angle was obtained. In conclusion, Pt-W alloy can be applied as the EUV mask absorber capable of fine patterning while improving the imaging performance.

Citation Download Citation

Yunsoo Kim, Dongmin Jeong, Minsun Cho, and Jinho Ahn "Alternative EUV mask with platinum-tungsten alloy for high-NA EUV lithography", Proc. SPIE PC12292, International Conference on Extreme Ultraviolet Lithography 2022, PC122920U (31 October 2022); https://doi.org/10.1117/12.2641805

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