Comprehensive focus-overlay-CD correlation to identify photolithographic performance

Mircea V. Dusa; Stephen Dellarochetta; Allen C. Fung; Bo Su; Terrence E. Zavecz

doi:10.1117/12.240922

7 June 1996 Comprehensive focus-overlay-CD correlation to identify photolithographic performance

Mircea V. Dusa, Stephen Dellarochetta, Allen C. Fung, Bo Su, Terrence E. Zavecz

Proceedings Volume 2726, Optical Microlithography IX; (1996) https://doi.org/10.1117/12.240922
Event: SPIE's 1996 International Symposium on Microlithography, 1996, Santa Clara, CA, United States

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.

Citation Download Citation

Mircea V. Dusa, Stephen Dellarochetta, Allen C. Fung, Bo Su, and Terrence E. Zavecz "Comprehensive focus-overlay-CD correlation to identify photolithographic performance", Proc. SPIE 2726, Optical Microlithography IX, (7 June 1996); https://doi.org/10.1117/12.240922

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