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Proceedings Paper

Wafer examination and critical dimension estimation using scattered light
Author(s): Richard H. Krukar; Susan M. Gaspar; Scott R. Wilson; Donald R. Hush; S. Sohail H. Naqvi; John Robert McNeil
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Paper Abstract

We have applied optical scatter techniques to improve several aspects of microelectronic manufacturing. One technique involves characterizing light scattered from two dimensional device structures, such as those from VLSI circuitry etched on a wafer, using a frosted dome which is imaged by a CCD camera. Previously, limited dynamic range available from affordable digital imaging systems has prevented the study of two dimensional scatter patterns. We have demonstrated a simple technique to increase the dynamic range by combining multiple images taken at different intensities. After the images have been acquired, image processing techniques are used to find and catalog the diffraction orders. Techniques such as inverse least squares, principal component analysis, and neural networks are then used to evaluate the dependence of the light scatter on a particular wafer characteristic under examination. Characterization of surface planarization over a VLSI structure and measurement of line edge roughness of diffraction gratings are presented as examples.

Paper Details

Date Published: 1 August 1992
PDF: 10 pages
Proc. SPIE 1661, Machine Vision Applications in Character Recognition and Industrial Inspection, (1 August 1992); doi: 10.1117/12.130298
Show Author Affiliations
Richard H. Krukar, Univ. of New Mexico (United States)
Susan M. Gaspar, Univ. of New Mexico (United States)
Scott R. Wilson, Univ. of New Mexico (United States)
Donald R. Hush, Univ. of New Mexico (United States)
S. Sohail H. Naqvi, Univ. of New Mexico (United States)
John Robert McNeil, Univ. of New Mexico (United States)

Published in SPIE Proceedings Vol. 1661:
Machine Vision Applications in Character Recognition and Industrial Inspection
Donald P. D'Amato; Wolf-Ekkehard Blanz; Byron E. Dom; Sargur N. Srihari, Editor(s)

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