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Proceedings Paper

Model-assisted complementary double exposure with source optimization
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Paper Abstract

Source optimization techniques fall into two contrasting categories: The first and most common category includes methods to minimize OPC complexity and maximize process window for a specific pattern, without guaranteeing adequate image quality for the rest of the layout. The second category includes methods which optimize source and mask concurrently to deliver the largest process window and maximum resolution. This approach however, provides minimum control in the manufacturability of the mask. Our formulation is a hybrid combination of both categories. We apply a model-assisted double exposure decomposition using pre-optimized sources. By adding a second exposure we minimize possible negative impacts that the pattern specific source may have over the whole layout, while providing control over the area of interest and taking into account realistic mask constraints. We applied this technique to an SRAM design and the surrounding logic. Because of the general formulation of the model-assisted decomposition, we do not explicitly select memory or periphery logic, since by construction this method determines which feature segments correspond to each of the available exposures. We quantify the lithographic performance of this technique against other RET options via a statistical analysis of CD control and ILS behavior.

Paper Details

Date Published: 6 December 2004
PDF: 9 pages
Proc. SPIE 5567, 24th Annual BACUS Symposium on Photomask Technology, (6 December 2004); doi: 10.1117/12.568576
Show Author Affiliations
J. Andres Torres, Mentor Graphics Corp. (United States)
Yuri Granik, Mentor Graphics Corp. (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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