18 April 2013 Quality metric for accurate overlay control in <20nm nodes
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Proceedings Volume 8681, Metrology, Inspection, and Process Control for Microlithography XXVII; 86811J (2013); doi: 10.1117/12.2011454
Event: SPIE Advanced Lithography, 2013, San Jose, California, United States
The semiconductor industry is moving toward 20nm nodes and below. As the Overlay (OVL) budget is getting tighter at these advanced nodes, the importance in the accuracy in each nanometer of OVL error is critical. When process owners select OVL targets and methods for their process, they must do it wisely; otherwise the reported OVL could be inaccurate, resulting in yield loss. The same problem can occur when the target sampling map is chosen incorrectly, consisting of asymmetric targets that will cause biased correctable terms and a corrupted wafer. Total measurement uncertainty (TMU) is the main parameter that process owners use when choosing an OVL target per layer. Going towards the 20nm nodes and below, TMU will not be enough for accurate OVL control. KLA-Tencor has introduced a quality score named ‘Qmerit’ for its imaging based OVL (IBO) targets, which is obtained on the-fly for each OVL measurement point in X & Y. This Qmerit score will enable the process owners to select compatible targets which provide accurate OVL values for their process and thereby improve their yield. Together with K-T Analyzer’s ability to detect the symmetric targets across the wafer and within the field, the Archer tools will continue to provide an independent, reliable measurement of OVL error into the next advanced nodes, enabling fabs to manufacture devices that meet their tight OVL error budgets.
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Dana Klein, Eran Amit, Guy Cohen, Nuriel Amir, Michael Har-Zvi, Chin-Chou Kevin Huang, Ramkumar Karur-Shanmugam, Bill Pierson, Cindy Kato, Hiroyuki Kurita, "Quality metric for accurate overlay control in <20nm nodes", Proc. SPIE 8681, Metrology, Inspection, and Process Control for Microlithography XXVII, 86811J (18 April 2013); doi: 10.1117/12.2011454; https://doi.org/10.1117/12.2011454

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