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Proceedings Paper

Illumination source mapping and optimization with resist based process metrics for low k1 imaging
Author(s): Guohong Zhang; Steve Hansen
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Paper Abstract

Pattern specific illuminator optimization is a key component in developing low k1 lithography solutions that utilize off-axis illumination schemes. Aerial image metrics such as NILS (normalized image log slope) have been used in the past to select the optimal illuminator source shape that yields the largest process margin such as DOF. A more practical and process orientated approach is presented in this paper with resist also included in the optimization scheme. Here pupil fill calculation is based on the actual process metrics such as DOF at certain exposure latitude, mask error enhancement factor (MEEF), mask bias (OPC), and CD uniformity (ACLV). A comparison is made with the conventional aerial image based approach. Examples are given to illustrate the advantages of the resist simulation based optimization scheme and its potential application in global process optimization by using a common, universal set of process metrics. This makes it possible to search for the optimal scanner optics settings through simulation techniques over a parameter space with many degrees of freedom, which is difficult to explore simply with limited empirical data collection. As a result, resist based illumination source optimization dramatically reduces the process development cycle, particularly for low k1 critical patterns.

Paper Details

Date Published: 28 May 2004
PDF: 12 pages
Proc. SPIE 5377, Optical Microlithography XVII, (28 May 2004); doi: 10.1117/12.536006
Show Author Affiliations
Guohong Zhang, Texas Instruments Inc. (United States)
Steve Hansen, ASML (United States)

Published in SPIE Proceedings Vol. 5377:
Optical Microlithography XVII
Bruce W. Smith, Editor(s)

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