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Proceedings Paper

Understanding illumination effects for control of optical proximity effects (OPE)
Author(s): Donis G. Flagello; Bernd Geh; Robert Socha; Peng Liu; Yu Cao; Roland Stas; Oliver Natt; Jörg Zimmermann
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Paper Abstract

Optical lithography has had great success in recent history in utilizing the most advanced optical technology to create NA=1.35 immersion lenses. These lenses have aberration levels at or below the 5m level. Much of this is due to advancements in lens design, materials, and aspheric polishing techniques. Now that the lenses are nearly "perfect", more attention is being given to the illuminator and its performance. This paper examines the fundamental metrics that are used to analyze the illumination source shape as it pertains to the optical proximity effect (OPE). It is found that the more traditional metric of partial coherence, σ, is often not sufficient to explain through pitch CD performance. Metrics are introduced to compare multiple sources and compared to their correlation to OPE with respect to a reference. A new parametric model for annular illumination is introduced and shown to correlate within an RMS=0.03nm of the OPE data.

Paper Details

Date Published: 12 March 2008
PDF: 15 pages
Proc. SPIE 6924, Optical Microlithography XXI, 69241U (12 March 2008); doi: 10.1117/12.773632
Show Author Affiliations
Donis G. Flagello, ASML US, Inc. (United States)
Bernd Geh, ASML US, Inc. (United States)
Robert Socha, ASML US, Inc. (United States)
Peng Liu, ASML Brion (United States)
Yu Cao, ASML Brion (United States)
Roland Stas, ASML (Netherlands)
Oliver Natt, Carl Zeiss SMT AG (Germany)
Jörg Zimmermann, Carl Zeiss SMT AG (Germany)

Published in SPIE Proceedings Vol. 6924:
Optical Microlithography XXI
Harry J. Levinson; Mircea V. Dusa, Editor(s)

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