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Proceedings Paper

Improving exposure latitudes and aligning best focus through pitch by curing M3D phase effects with controlled aberrations
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Paper Abstract

We show, in simulation and by wafer exposures, how to improve an EUV Single Exposure Metal direct print at NA 0.33. Based on a fundamental understanding of Mask 3D effects, we show how to design a pupil in conjunction with induced aberrations to cure the M3D phase effects. For L/S through pitch, we increase NILS/exposure latitude by ~10%, reduce the best focus range by two thirds, and reduce Bossung tilts. Simultaneously, we reduce tip-to-tip (T2T) CD by 1-4nm at constant exposure latitude and LCDU. In EUV, M3D effects lead to phase modulation of the diffracted orders. This results in relative pattern shifts of images coming from different pixels in the pupil. We find that these pattern shifts are pole specific as M3D phase effects effectively induce phase tilts of opposite sign for opposite poles. This results in a pattern independent aerial image shifts for each pole. Here we show how these shifts can explain M3D phase effects (NILS loss by fading, best focus through pitch variation, Bossung tilts) and how they drive source optimization. Furthermore, we show how it is possible to counteract these M3D effects. Disentangling the diffraction orders, so that each point in the pupil plane is passed only by a single diffraction order, we can find a suitable aberration (Z6 for L/S) that effectively introduces a phase tilt of opposite sign per pole and cures the M3D effects. The idea is also applicable to other use cases: For dense contact holes we need to inject a phase front that shifts 0th against 1st order phase.

Paper Details

Date Published: 26 September 2019
PDF: 20 pages
Proc. SPIE 11147, International Conference on Extreme Ultraviolet Lithography 2019, 111470E (26 September 2019); doi: 10.1117/12.2537104
Show Author Affiliations
Joern-Holger Franke, IMEC (Belgium)
Joost Bekaert, IMEC (Belgium)
Victor Blanco, IMEC (Belgium)
Lieve Van Look, IMEC (Belgium)
Felix Wahlisch, ASML Netherlands B.V. (Netherlands)
Kateryna Lyakhova, ASML Netherlands B.V. (Netherlands)
Paul van Adrichem, ASML Netherlands B.V. (Netherlands)
Mark John Maslow, ASML Netherlands B.V. (Netherlands)
Guido Schiffelers, ASML Netherlands B.V. (Netherlands)
Eric Hendrickx, IMEC (Belgium)

Published in SPIE Proceedings Vol. 11147:
International Conference on Extreme Ultraviolet Lithography 2019
Toshiro Itani; Paolo A. Gargini; Patrick P. Naulleau; Kurt G. Ronse, Editor(s)

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