Depth of focus in high-NA EUV lithography: the role of assist features and their variability budget

Roel Gronheid; Alex Vaglio Pret; Anatoly Burov

doi:10.1117/12.2658394

28 April 2023 Depth of focus in high-NA EUV lithography: the role of assist features and their variability budget

Roel Gronheid, Alex Vaglio Pret, Anatoly Burov

Proceedings Volume 12494, Optical and EUV Nanolithography XXXVI; 124940O (2023) https://doi.org/10.1117/12.2658394
Event: SPIE Advanced Lithography + Patterning, 2023, San Jose, California, United States

Abstract

In this paper, the role of sub-resolution assist features (SRAFs) in 0.55NA EUV lithography is discussed. We demonstrate how SRAFs help with pattern placement error (PPE) control through exposure focus on horizontal line/space structures using dark field masks. Even for 26nm minimum pitch design rules (relatively high k1), SRAFs help control the focus budget. Next, an analysis of the mask variability budget is done. We establish that a tight CD and placement control on the SRAFs is required for keeping PPE through focus under control. A variability budget of 0.5nm (1X) for both CD and PPE is shown to be just sufficient for maintaining a 40nm depth of focus (DoF) in the absence of process variability. PPE variability due to resist stochastics further reduces the available DoF.

Conference Presentation

Citation Download Citation

Roel Gronheid, Alex Vaglio Pret, and Anatoly Burov "Depth of focus in high-NA EUV lithography: the role of assist features and their variability budget", Proc. SPIE 12494, Optical and EUV Nanolithography XXXVI, 124940O (28 April 2023); https://doi.org/10.1117/12.2658394

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