21 April 2014 Innovative fast technique for overlay accuracy estimation using archer self calibration (ASC)
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Abstract
As overlay margins shrink for advanced process nodes, a key overlay metrology challenge is finding the measurement conditions which optimize the yield for every device and layer. Ideally, this setup should be found in-line during the lithography measurements step. Moreover, the overlay measurement must have excellent correlation to the device electrical behavior. This requirement makes the measurement conditions selection even more challenging since it requires information about the response of both the metrology target and device to different process variations. In this work a comprehensive solution for overlay metrology accuracy, used by UMC, is described. This solution ranks the different measurement setups by their accuracy, using Qmerit, as reported by the Archer 500. This ranking was verified to match device overlay using electrical tests. Moreover, the use of Archer Self Calibration (ASC) allows further improvement of overlay measurement accuracy.
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Simon C. C. Hsu, Simon C. C. Hsu, Charlie Chen, Charlie Chen, Chun Chi Yu, Chun Chi Yu, Yuan Chi Pai, Yuan Chi Pai, Eran Amit, Eran Amit, Lipkong Yap, Lipkong Yap, Tal Itzkovich, Tal Itzkovich, David Tien, David Tien, Eros Huang, Eros Huang, Kelly T. L. Kuo, Kelly T. L. Kuo, Nuriel Amir, Nuriel Amir, } "Innovative fast technique for overlay accuracy estimation using archer self calibration (ASC)", Proc. SPIE 9050, Metrology, Inspection, and Process Control for Microlithography XXVIII, 90501N (21 April 2014); doi: 10.1117/12.2046670; https://doi.org/10.1117/12.2046670
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