13 March 2018 Accuracy optimization with wavelength tunability in overlay imaging technology
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Abstract
As semiconductor manufacturing technology progresses and the dimensions of integrated circuit elements shrink, overlay budget is accordingly being reduced. Overlay budget closely approaches the scale of measurement inaccuracies due to both optical imperfections of the measurement system and the interaction of light with geometrical asymmetries of the measured targets. Measurement inaccuracies can no longer be ignored due to their significant effect on the resulting device yield. In this paper we investigate a new approach for imaging based overlay (IBO) measurements by optimizing accuracy rather than contrast precision, including its effect over the total target performance, using wavelength tunable overlay imaging metrology. We present new accuracy metrics based on theoretical development and present their quality in identifying the measurement accuracy when compared to CD-SEM overlay measurements. The paper presents the theoretical considerations and simulation work, as well as measurement data, for which tunability combined with the new accuracy metrics is shown to improve accuracy performance.
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Honggoo Lee, Yoonshik Kang, Sangjoon Han, Kyuchan Shim, Minhyung Hong, Seungyoung Kim, Jieun Lee, Dongyoung Lee, Eungryong Oh, Ahlin Choi, Youngsik Kim, Tal Marciano, Dana Klein, Eitan M. Hajaj, Sharon Aharon , Guy Ben-Dov , Saltoun Lilach, Dan Serero, Anna Golotsvan, "Accuracy optimization with wavelength tunability in overlay imaging technology", Proc. SPIE 10585, Metrology, Inspection, and Process Control for Microlithography XXXII, 1058532 (13 March 2018); doi: 10.1117/12.2300153; https://doi.org/10.1117/12.2300153
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