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Proceedings Paper

High-resolution optical overlay metrology
Author(s): Richard M. Silver; Ravikiran Attota; Michael Stocker; Michael Bishop; Jau-Shi Jay Jun; Egon Marx; Mark P. Davidson; Robert D. Larrabee
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Paper Abstract

Optical methods are often thought to lose their effectiveness as a metrology tool beyond the Rayleigh criterion. However, using advanced modeling methods, the conventional resolution limitations encountered in well-defined edge-to-edge measurements using edge thresholds do not apply. In fact, in this paper we present evidence that optics can be used to image and measure features as small as 10 nm in dimension, well below the imaging wavelength. To understand the limits of optical methods we have extensively studied both linewidth and overlay metrology applications. Although overlay applications are usually thought to involve pitch or centerline measurements of features from different process levels, some target designs present optical proximity effects which pose a significant challenge. Likewise, line width measurements require determination of the physical edges and geometry which created that profile. Both types of measurements require model-based analysis to accurately evaluate the data and images. In this paper we explore methods to optimize target geometry, optical configurations, structured illumination, and analysis algorithms with applications in both critical dimension and overlay metrology.

Paper Details

Date Published: 24 May 2004
PDF: 18 pages
Proc. SPIE 5375, Metrology, Inspection, and Process Control for Microlithography XVIII, (24 May 2004); doi: 10.1117/12.539028
Show Author Affiliations
Richard M. Silver, National Institute of Standards and Technology (United States)
Ravikiran Attota, National Institute of Standards and Technology (United States)
Michael Stocker, National Institute of Standards and Technology (United States)
Michael Bishop, International SEMATECH (United States)
Jau-Shi Jay Jun, National Institute of Standards and Technology (United States)
Egon Marx, National Institute of Standards and Technology (United States)
Mark P. Davidson, Spectel Company (United States)
Robert D. Larrabee, National Institute of Standards and Technology (United States)


Published in SPIE Proceedings Vol. 5375:
Metrology, Inspection, and Process Control for Microlithography XVIII
Richard M. Silver, Editor(s)

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