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19 May 2008 Source optimization and mask design to minimize MEEF in low k1 lithography
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Proceedings Volume 7028, Photomask and Next-Generation Lithography Mask Technology XV; 70280T (2008)
Event: Photomask and NGL Mask Technology XV, 2008, Yokohama, Japan
Mask Error Enhancement Factor (MEEF) plays an increasingly important role in the DFM flow required to continue shrinking designs in the low-k1 lithography regime. The ability to understand and minimize MEEF during design optimization and RET application is essential to obtain a usable process window. The traditional limited-cutline approach to analyzing and characterizing MEEF is no longer sufficient to accommodate increasing design complexity. In this paper, we present a new method of edge-based MEEF for analyzing and characterizing MEEF-based hot spots that overcomes the limitations of the traditional cutline approach. Application of the technique to analyze full-field pixel-based two dimensional (2D) MEEF color maps of several different design clips is explained. Process window (PW) is the most important metric in lithography simulations for evaluating the performance of a given RET solution. Traditionally, process window calculation assumes a perfect mask, with no mask errors or corner rounding. In a low k1 regime, MEEF increases enough that mask errors can no longer be ignored in PW evaluation. A method of calculating "MEEF-aware" common process windows and creating a MEEF-aware process variation (PV) band, including mask bias, is presented, and wafer image variability is examined under several process variations, including dose, defocus and mask error. Results of MEEF-aware source-mask optimization (SMO) and design rule exploration using inverse lithography technology (ILT) are also presented.
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Guangming Xiao, Tom Cecil, Lingyong Pang, Bob Gleason, and John McCarty "Source optimization and mask design to minimize MEEF in low k1 lithography", Proc. SPIE 7028, Photomask and Next-Generation Lithography Mask Technology XV, 70280T (19 May 2008);

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