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Proceedings Paper

Intercomparison of SEM, AFM, and electrical linewidths
Author(s): John S. Villarrubia; Ronald G. Dixson; Samuel N. Jones; Jeremiah R. Lowney; Michael T. Postek; Richard A. Allen; Michael W. Cresswell
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Paper Abstract

Uncertainty in the locations of line edges dominates the uncertainty budget for high quality sub-micrometer linewidth measurements. For microscopic techniques like scanning electron microscopy (SEM) and atomic force microscopy (AFM), the image of the sharp edge is broadened due to the instrument's non-ideal response. Localizing the true edge position within its broadened image requires a model for the instrument-sample interaction. Ideal left and right edges are mirror images of one another, so any modeling error in the position assignment will have opposite signs for the two types of edges. Linewidth measurements inherently involves such opposite edges and consequent doubling of model errors. Similar considerations apply to electrical critical dimension (ECD) measurement. Although ECD is a non-imaging technique, one must still model the offset between the position of the physical edge and the effective edge of the conducting part of the line. One approach to estimating the reliability of existing models is to compare result when fundamentally different instruments measure the same line. We have begun a project to perform such an intercomparison, and we report here initial results for SEM, AFM, and ECD measurements of sub-micrometer lines in single crystal Si. Edge positions are determined from SEM images using Monte Carlo tracing of electron trajectories to predict the edge shape.In the AFM, we estimate and correct for tip geometry using tools from mathematical morphology. ECD measurements are corrected for band bending in the neighborhood of the edges.

Paper Details

Date Published: 14 June 1999
PDF: 12 pages
Proc. SPIE 3677, Metrology, Inspection, and Process Control for Microlithography XIII, (14 June 1999); doi: 10.1117/12.350846
Show Author Affiliations
John S. Villarrubia, National Institute of Standards and Technology (United States)
Ronald G. Dixson, National Institute of Standards and Technology (United States)
Samuel N. Jones, National Institute of Standards and Technology (United States)
Jeremiah R. Lowney, National Institute of Standards and Technology (United States)
Michael T. Postek, National Institute of Standards and Technology (United States)
Richard A. Allen, National Institute of Standards and Technology (United States)
Michael W. Cresswell, National Institute of Standards and Technology (United States)


Published in SPIE Proceedings Vol. 3677:
Metrology, Inspection, and Process Control for Microlithography XIII
Bhanwar Singh, Editor(s)

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