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Proceedings Paper

Achievements and challenges of EUV mask imaging
Author(s): Natalia Davydova; Eelco van Setten; Robert de Kruif; Brid Connolly; Norihito Fukugami; Yutaka Kodera; Hiroaki Morimoto; Yo Sakata; Jun Kotani; Shinpei Kondo; Tomohiro Imoto; Haiko Rolff; Albrecht Ullrich; Ad Lammers; Guido Schiffelers; Joep van Dijk
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Paper Abstract

The impact of various mask parameters on CDU combined in a total mask budget is presented, for 22 nm lines, for reticles used for NXE:3300 qualification. Apart from the standard mask CD measurements, actinic spectrometry of multilayer is used to qualify reflectance uniformity over the image field; advanced 3D metrology is applied for absorber profile characterization including absorber height and side wall angle. The predicted mask impact on CDU is verified using actual exposure data collected on multiple NXE:3300 scanners. Mask 3D effects are addressed, manifesting themselves in best focus shifts for different structures exposed with off-axis illumination. Experimental NXE:3300 results for 16 nm dense lines and 20 nm (semi-)isolated spaces are shown: best focus range reaches 24 nm. A mitigation strategy by absorber height optimization is proposed based on experimental results of a special mask with varying absorber heights. Further development of a black image border for EUV mask is considered. The image border is a pattern free area surrounding image field preventing exposure the image field neighborhood on wafer. Normal EUV absorber is not suitable for this purpose as it has 1-3% EUV reflectance. A current solution is etching of ML down to substrate reducing EUV reflectance to <0.05%. A next step in the development of the black border is the reduction of DUV Out-of-Band reflectance (<1.5%) in order to cope with DUV light present in EUV scanners. Promising results achieved in this direction are shown.

Paper Details

Date Published: 28 July 2014
PDF: 11 pages
Proc. SPIE 9256, Photomask and Next-Generation Lithography Mask Technology XXI, 925602 (28 July 2014); doi: 10.1117/12.2072945
Show Author Affiliations
Natalia Davydova, ASML Netherlands B.V. (Netherlands)
Eelco van Setten, ASML Netherlands B.V. (Netherlands)
Robert de Kruif, ASML Netherlands B.V. (Netherlands)
Brid Connolly, Toppan Photomasks, Inc. (Germany)
Norihito Fukugami, Toppan Printing Co., Ltd. (Japan)
Yutaka Kodera, Toppan Printing Co., Ltd. (Japan)
Hiroaki Morimoto, Toppan Printing Co., Ltd. (Japan)
Yo Sakata, Toppan Printing Co., Ltd. (Japan)
Jun Kotani, Toppan Printing Co., Ltd. (Japan)
Shinpei Kondo, Toppan Printing Co., Ltd. (Japan)
Tomohiro Imoto, Toppan Printing Co., Ltd. (Japan)
Haiko Rolff, Advanced Mask Technology Ctr. GmbH Co. KG (Germany)
Albrecht Ullrich, Advanced Mask Technology Ctr. GmbH Co. KG (Germany)
Ad Lammers, ASML Netherlands B.V. (Netherlands)
Guido Schiffelers, ASML Netherlands B.V. (Netherlands)
Joep van Dijk, ASML Netherlands B.V. (Netherlands)

Published in SPIE Proceedings Vol. 9256:
Photomask and Next-Generation Lithography Mask Technology XXI
Kokoro Kato, Editor(s)

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