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Proceedings Paper

Picometer-scale accuracy in pitch metrology by optical diffraction and atomic force microscopy
Author(s): Donald A. Chernoff; Egbert Buhr; David L. Burkhead; Alexander Diener
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Paper Abstract

We measured the pitch of a 144-nm pitch, two-dimensional grid in two different laboratories. Optical Diffraction gave very high accuracy for mean pitch and Atomic Force Microscopy measured individual pitch values, gaining additional information about local pitch variation. The measurements were made traceable to the international meter. Optical diffraction gave mean value 143.928 ± 0.015 nm (95% confidence limit, per GUM). AFM gave mean value 143.895 ± 0.079 nm. Individual pitch values had standard deviation 0.55 nm and expanded uncertainty ± 1.1 nm. Mean values measured by the two methods agreed within 0.033 nm. Because this was less than the uncertainty due to random variation in the AFM results, it suggests that the AFM measuring and analysis procedures have successfully corrected all systematic errors of practical significance in microscopy. We also discuss what precision may be expected from the AFM method when it is applied to measure smaller pitches.

Paper Details

Date Published: 25 March 2008
PDF: 11 pages
Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 69223J (25 March 2008); doi: 10.1117/12.768429
Show Author Affiliations
Donald A. Chernoff, Advanced Surface Microscopy, Inc. (United States)
Egbert Buhr, Physikalisch-Technische Bundesanstalt (Germany)
David L. Burkhead, Advanced Surface Microscopy, Inc. (United States)
Alexander Diener, Physikalisch-Technische Bundesanstalt (Germany)

Published in SPIE Proceedings Vol. 6922:
Metrology, Inspection, and Process Control for Microlithography XXII
John A. Allgair; Christopher J. Raymond, Editor(s)

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