13 March 2012 Influence of SRAF size on main feature CD variation on advanced node
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The mask error budget continues to shrink with device pitch. In advance node, mask error enhancement factor (MEEF) will increases up to over 4. The impact of assistant feature size on main feature CD variation becomes more obvious than before. Generally, sub-resolution assist feature (SRAF) use is an indispensable technique to provide adequate depth of focus (DOF) for larger pitches on layers with lithography settings that are optimized for denser pitches. But, SRAF width will be critical issue with shrinking design rule. We investigated the impact of the assist feature size on through pitch patterns. Using M3D (mask 3Dimension) model of Prolith simulation tool, we simulate the main pattern variation by adjusting assistant feature size [1]. SRAF printability also be concerned through simulation and be verified by real wafer printing result. We show that the wafer CD impact that come form mask CD variation of main feature and the influence of assistant feature size on dense main feature become more and more.
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Wei Cyuan Lo, Wei Cyuan Lo, Yi Chou Chen, Yi Chou Chen, Yung Feng Cheng, Yung Feng Cheng, Ming Jui Chen, Ming Jui Chen, } "Influence of SRAF size on main feature CD variation on advanced node", Proc. SPIE 8326, Optical Microlithography XXV, 83262K (13 March 2012); doi: 10.1117/12.917989; https://doi.org/10.1117/12.917989

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