Optimizations aspects for EUV low-k1 logic with the low-n mask

M.-Claire van Lare; Stephen Hsu; Jo Finders; Olena Romanets

doi:10.1117/12.2600998

13 October 2021 Optimizations aspects for EUV low-k1 logic with the low-n mask

M.-Claire van Lare, Stephen Hsu, Jo Finders, Olena Romanets

Proceedings Volume 11854, International Conference on Extreme Ultraviolet Lithography 2021; 1185412 (2021) https://doi.org/10.1117/12.2600998
Event: SPIE Photomask Technology + EUV Lithography, 2021, Online Only

Abstract

Experimental results demonstrated that the EUV low-n mask improves both LCDU and dose for dense features. For semi-isolated and isolated features best-focus shifts through pitch can occur with the low-n mask as well as with the Tabased mask. In this paper, we show how mask-3D induced phase offsets between diffraction orders lead to best focus shifts for dense and (semi-) isolated features. Subsequently we investigate what are the options to mitigate best focus shifts. First, when the pitch is large enough, sub-resolution assist features (SRAFs) can significantly improve contrast and reduce best-focus shifts. Second, optimizing the target and mask bias, is very effective for focus-shift mitigation. Especially the low-n mask shows a strong response to target and mask bias. Third, using bright field imaging instead of dark-field imaging generally also results in smaller best focus shifts through pitch. Using source-mask optimization (SMO) examples through pitch, we show how these mitigation strategies are effectively applied to through pitch use cases. We find NILS DOF improvements up to 65% with the low-n mask and optimized retargeting.

Conference Presentation

Citation Download Citation

M.-Claire van Lare, Stephen Hsu, Jo Finders, and Olena Romanets "Optimizations aspects for EUV low-k1 logic with the low-n mask", Proc. SPIE 11854, International Conference on Extreme Ultraviolet Lithography 2021, 1185412 (13 October 2021); https://doi.org/10.1117/12.2600998

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