4 September 2015 OPC verification considering CMP induced topography
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Proceedings Volume 9661, 31st European Mask and Lithography Conference; 96610E (2015) https://doi.org/10.1117/12.2196646
Event: 31st European Mask and Lithography Conference, 2015, Eindhoven, Netherlands
Abstract
OPC Verification is important to identify the critical wafer hotspots prior to mask fabrication. It helps to identify process limiting structures and possible yield limiters. These hotspots are also used by litho engineers to set up process conditions upfront. OPC Verification generally involves verification done at nominal and process window conditions. The process window conditions take into consideration typical process variations for lithography. In this standard flow, the post CMP topography variation was also lumped into these process variations via focus. But in current technologies especially in higher metal layers, CMP induced topography variation has become a major contributor to limit the overall process window. This results in different best focus for structures with different topography. This gives rises to requirement of OPC Verification flow taking into account these location-specific variations in order to know if the mask data can be used or not. This paper proposes a method to incorporate the topography induced focus shift into the OPC Verification flow. OPC Verification checks are performed at the new nominal and Process window conditions to identify the real hotspots seen on wafer. Results are shown where the highlighted hotspots with the proposed new flow correlate better with wafer results. Runtime was also taken into consideration when the flow was developed. Experiments on various products show better accuracy with minimal runtime impact.
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Rakesh Kumar Kuncha, Aravind Narayana Samy, Ushasree Katakamsetty, "OPC verification considering CMP induced topography", Proc. SPIE 9661, 31st European Mask and Lithography Conference, 96610E (4 September 2015); doi: 10.1117/12.2196646; https://doi.org/10.1117/12.2196646
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