Wafer-level measurement using autofocus

Norihiro Yamamoto; Katsuyoshi Kobayashi; Kenji Nakagawa

doi:10.1117/12.240974

7 June 1996 Wafer-level measurement using autofocus

Norihiro Yamamoto, Katsuyoshi Kobayashi, Kenji Nakagawa

Author Affiliations +

Proceedings Volume 2726, Optical Microlithography IX; (1996) https://doi.org/10.1117/12.240974
Event: SPIE's 1996 International Symposium on Microlithography, 1996, Santa Clara, CA, United States

Abstract

Because the depth of focus is decreasing with reduction of feature size, we cannot ignore the wafer leveling. In this issue, we report that we suppressed the wafer inclination error by using enhanced global leveling (EGL) in which the wafer inclination is measured by auto-focus on several sampling points, and confirmed the improvement of the line width control. The EGL method corrects the wafer leveling error on the basis of the wafer inclination calculated accurately by auto-focus measurement. Therefore, to ensure an accurate wafer inclination measurement, we optimized the auto-focus measurement parameters for EGL. As a result, we found the suppression of the leveling gap within 0.2 micrometers or less in 22 mm square field when we made the auto-focus measurement at the centers of the adjacent shot. And we confirmed the improvement of the line width control on real device wafers with EGL.

Citation Download Citation

Norihiro Yamamoto, Katsuyoshi Kobayashi, and Kenji Nakagawa "Wafer-level measurement using autofocus", Proc. SPIE 2726, Optical Microlithography IX, (7 June 1996); https://doi.org/10.1117/12.240974

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