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Proceedings Paper

Toward accurate linewidth metrology using atomic force microscopy and tip characterization
Author(s): Ronald G. Dixson; Jason Schneir; Thomas H. McWaid; Neal T. Sullivan; Vincent Wen-Chieh Tsai; Saleem H. Zaidi; Steven R. J. Brueck
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Paper Abstract

Atomic force microscopes (AFMs) are potentially capable of dimensional metrology with nanometer scale accuracy. Feature width measurements, however, can be severely affected by the size of an AFM probe. Indeed, for features with sufficiently steep sidewalls, a conical AFM probe may only be able to measure the width near the top of a line, with much of the apparent width at the bottom being due to the size of the probe. Although the probe contribution to the apparent feature width is generally much smaller at the top, it is often not negligible. Thus, the accuracy and value of such 'top width' measurements could potentially be improved by using another sample to independently characterize the geometry of the tip and correcting the measured top width for the finite size of the probe. We performed a test of this measurement scheme by using the NIST calibrated atomic force microscope (C-AFM), an AFM with metrology traceable to the wavelength of light, to perform top width measurements on a sample of preferentially etched Si lines. Samples of mica with nanometer sized colloidal particles deposited on them were used to characterize the C-AFM tips, and thus correct apparent top width measurements for the probe size. Except when probe damage during a measurement was severe, comparisons of the C-AFM results with cross sectional TEM yielded good agreement with uncertainties at the level of 30 nm (2 sigma).

Paper Details

Date Published: 21 May 1996
PDF: 19 pages
Proc. SPIE 2725, Metrology, Inspection, and Process Control for Microlithography X, (21 May 1996); doi: 10.1117/12.240131
Show Author Affiliations
Ronald G. Dixson, National Institute of Standards and Technology (United States)
Jason Schneir, National Institute of Standards and Technology (United States)
Thomas H. McWaid, National Institute of Standards and Technology (United States)
Neal T. Sullivan, Digital Equipment Corp. (United States)
Vincent Wen-Chieh Tsai, Univ. of Maryland/College Park (United States)
Saleem H. Zaidi, Univ. of New Mexico (United States)
Steven R. J. Brueck, Univ. of New Mexico (United States)

Published in SPIE Proceedings Vol. 2725:
Metrology, Inspection, and Process Control for Microlithography X
Susan K. Jones, Editor(s)

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