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Proceedings Paper

Placing assist features in layout using a process model
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Paper Abstract

Sub-resolution assist features (SRAFs) are non-printing features arranged on a mask layout to “assist” the lithographic performance of the lines intended to be printed on the wafer [1]. SRAFs typically are narrow lines located adjacent to the target figure edges. Current practice is to synthesize SRAFs with a rule-based methodology where the assist feature placement is dictated by combinations of feature width and spacing parameters. Optical behavior with off-axis illumination is complex and requires an elaborate set of SRAF synthesis rules. Creating and maintaining a robust set of placement rules guaranteed to work properly for arbitrary configurations is very difficult. Socha, et al, have demonstrated that the optimum configurations for SRAFs can be derived from the aerial image of the target layout configuration [2]. In this paper we show how SRAF synthesis can be optimally implemented in an OPC tool environment, leveraging lithography simulation.

Paper Details

Date Published: 6 December 2004
PDF: 7 pages
Proc. SPIE 5567, 24th Annual BACUS Symposium on Photomask Technology, (6 December 2004); doi: 10.1117/12.569179
Show Author Affiliations
Lawrence S. Melvin III, Synopsys, Inc. (United States)
James P. Shiely, Synopsys, Inc. (United States)
Michael L. Rieger, Synopsys, Inc. (United States)

Published in SPIE Proceedings Vol. 5567:
24th Annual BACUS Symposium on Photomask Technology
Wolfgang Staud; J. Tracy Weed, Editor(s)

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