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Proceedings Paper

Investigation of interactions between metrology and lithography with a CD SEM simulator
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Paper Abstract

The predictive power of computational lithography is often demonstrated by showing predicted 2D pattern shapes compared with top-down SEM images. However, image formation in a SEM is a complex process [1,2,3], and for most 3D lithography and OPC simulators, line width measurements and 2D pattern shapes are based on extracted resist polygons at a fixed height above the substrate. Generating resist polygon shapes with this method is driven by computationally efficiency instead of an attempt to describe the image formation process in an actual SEM. We present PROLITH photolithography simulations combined with simulation of the CD SEM to investigate the interactions between lithography and metrology. Our CD SEM simulator is a simplification of the complicated image formation process [4], but it captures many effects seen experimentally. For example, narrow trenches and contact holes are dark at the bottom in our simulated SEM images, while for isolated lines, the sidewall of the photoresist can clearly be observed all the way to the resist foot at the substrate. This simple result has important implications when evaluating lithographic phenomena such as LWR: for polygon-based metrology, simulated LWR is approximately constant with resist thickness; by contrast, the LWR increases with decreasing thickness when the same simulated 3D resist profiles are evaluated with the CD SEM simulator.

Paper Details

Date Published: 27 March 2014
PDF: 11 pages
Proc. SPIE 9051, Advances in Patterning Materials and Processes XXXI, 905109 (27 March 2014); doi: 10.1117/12.2048247
Show Author Affiliations
Mark D. Smith, KLA-Tencor Corp. (United States)
Chao Fang, KLA-Tencor Corp. (United States)
John J. Biafore, KLA-Tencor Corp. (United States)
Alessandro Vaglio Pret, KLA-Tencor Corp. (United States)
Stewart A. Robertson, KLA-Tencor Corp. (United States)

Published in SPIE Proceedings Vol. 9051:
Advances in Patterning Materials and Processes XXXI
Thomas I. Wallow; Christoph K. Hohle, Editor(s)

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