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Proceedings Paper

Impact of illumination source symmetrization in OPC
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Paper Abstract

It is well known that optical proximity effects are highly dependent upon the details of the illumination source. Tremendous effort is taken to match illumination source profiles between tools, as well as to appropriately represent the source intensity distribution in the models used for OPC and post-OPC verification. OPC software typically models the intensity profile in such a manner that empirical fitting of the CD data during model calibration can result in a representation of the "effective" source. In some cases, an actual measured source profile is available and can be referenced directly in the OPC recipe. However, it is common to average the 4 quadrants of a measured source profile such that the source representation is symmetrical about the x and y axes. This is done so that optical proximity correction can be applied hierarchically, with a single correction applied to a cell which may be instantiated in multiple orientations within the chip. It has generally been accepted that the positive runtime benefit accompanying this symmetrization is beneficial relative to any potential accuracy loss for cells oriented in different directions. In this paper, we investigate the impact of real source profile asymmetries on identical features with different orientations.

Paper Details

Date Published: 19 May 2008
PDF: 10 pages
Proc. SPIE 7028, Photomask and Next-Generation Lithography Mask Technology XV, 70283M (19 May 2008); doi: 10.1117/12.799411
Show Author Affiliations
John L. Sturtevant, Mentor Graphics Corp. (United States)
Le Hong, Mentor Graphics Corp. (United States)
Srividya Jayaram, Mentor Graphics Corp. (United States)
Stephen P. Renwick, Nikon Precision (United States)
Martin McCallum, Nikon Precision Europe GmbH (United Kingdom)
Peter De Bisschop, IMEC (Belgium)

Published in SPIE Proceedings Vol. 7028:
Photomask and Next-Generation Lithography Mask Technology XV
Toshiyuki Horiuchi, Editor(s)

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