11 May 2009 Model-based assist features
Author Affiliations +
Proceedings Volume 7379, Photomask and Next-Generation Lithography Mask Technology XVI; 73792Z (2009) https://doi.org/10.1117/12.824350
Event: Photomask and NGL Mask Technology XVI, 2009, Yokohama, Japan
We present a model-based method of generating and optimizing sub-resolution assist features. Assist feature generation is based on a focus sensitivity map derived from a cost function that minimizes the variations in the printed pattern with respect to focus change. We also demonstrate a method to generate mask-friendly SRAF polygons from the focus sensitivity map. After model-based placement, assist features and the main polygons are optimized together by moving their edge segments. One of the optimization goals is that side-lobes and assist features should not print. This is enforced by computing image on a two dimensional grid. We demonstrate the process window improvement for a contact layer example.
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Bayram Yenikaya, Oleg Alexandrov, Steven Chen, Anwei Liu, Ali Mokhberi, Apo Sezginer, "Model-based assist features", Proc. SPIE 7379, Photomask and Next-Generation Lithography Mask Technology XVI, 73792Z (11 May 2009); doi: 10.1117/12.824350; https://doi.org/10.1117/12.824350

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