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Proceedings Paper

Comprehensive focus-overlay-CD correlation to identify photolithographic performance
Author(s): Mircea V. Dusa; Stephen Dellarochetta; Allen C. Fung; Bo Su; Terrence E. Zavecz
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Paper Abstract

In this study we evaluate the focus budget of an i-line stepper, examining the sources of focus erosion for a 0.40 micrometers process. The analysis first examines the best focus of the system as predicted by the several common tools currently used in the industry. Using the overlay focus- monitor, we then determine the value of lens aberrations such as astigmatism and field curvature. The results of lens heating examined for the lens using these common techniques. A model describing the focus aberrations is then developed and applied to the data. This model uses data derived from the focus monitor to determine lens errors such as coma, astigmatism and field curvature. Using this model, data gathered over various numerical aperture and partial coherence values are evaluated to determine the variation of lens aberrations over their range and the depth of focus. Finally, data consisting of critical dimension information gathered using an commercial, automated SEM is used to validate the predictions of the focus model.

Paper Details

Date Published: 7 June 1996
PDF: 10 pages
Proc. SPIE 2726, Optical Microlithography IX, (7 June 1996); doi: 10.1117/12.240922
Show Author Affiliations
Mircea V. Dusa, National Semiconductor Corp. (United States)
Stephen Dellarochetta, National Semiconductor Corp. (United States)
Allen C. Fung, National Semiconductor Corp. (United States)
Bo Su, National Semiconductor Corp. (United States)
Terrence E. Zavecz, TEA Systems Corp. (United States)

Published in SPIE Proceedings Vol. 2726:
Optical Microlithography IX
Gene E. Fuller, Editor(s)

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