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Proceedings Paper

A complete methodology towards accuracy and lot-to-lot robustness in on-product overlay metrology using flexible wavelength selection
Author(s): Kaustuve Bhattacharyya; Arie den Boef; Marc Noot; Omer Adam; Grzegorz Grzela; Andreas Fuchs; Martin Jak; Sax Liao; Ken Chang; Vincent Couraudon; Eason Su; Wilson Tzeng; Cathy Wang; Christophe Fouquet; Guo-Tsai Huang; Kai-Hsiung Chen; Y. C. Wang; Kevin Cheng; Chih-Ming Ke; L. G. Terng
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Paper Abstract

The optical coupling between gratings in diffraction-based overlay triggers a swing-curve1,6 like response of the target’s signal contrast and overlay sensitivity through measurement wavelengths and polarizations. This means there are distinct measurement recipes (wavelength and polarization combinations) for a given target where signal contrast and overlay sensitivity are located at the optimal parts of the swing-curve that can provide accurate and robust measurements. Some of these optimal recipes can be the ideal choices of settings for production. The user has to stay away from the non-optimal recipe choices (that are located on the undesirable parts of the swing-curve) to avoid possibilities to make overlay measurement error that can be sometimes (depending on the amount of asymmetry and stack) in the order of several “nm”. To accurately identify these optimum operating areas of the swing-curve during an experimental setup, one needs to have full-flexibility in wavelength and polarization choices. In this technical publication, a diffraction-based overlay (DBO) measurement tool with many choices of wavelengths and polarizations is utilized on advanced production stacks to study swing-curves. Results show that depending on the stack and the presence of asymmetry, the swing behavior can significantly vary and a solid procedure is needed to identify a recipe during setup that is robust against variations in stack and grating asymmetry. An approach is discussed on how to use this knowledge of swing-curve to identify recipe that is not only accurate at setup, but also robust over the wafer, and wafer-to-wafer. KPIs are reported in run-time to ensure the quality / accuracy of the reading (basically acting as an error bar to overlay measurement).

Paper Details

Date Published: 28 March 2017
PDF: 10 pages
Proc. SPIE 10145, Metrology, Inspection, and Process Control for Microlithography XXXI, 101450A (28 March 2017); doi: 10.1117/12.2257662
Show Author Affiliations
Kaustuve Bhattacharyya, ASML Netherlands B.V. (Netherlands)
Arie den Boef, ASML Netherlands B.V. (Netherlands)
Marc Noot, ASML Netherlands B.V. (Netherlands)
Omer Adam, ASML Netherlands B.V. (Netherlands)
Grzegorz Grzela, ASML Netherlands B.V. (Netherlands)
Andreas Fuchs, ASML Netherlands B.V. (Netherlands)
Martin Jak, ASML Netherlands B.V. (Netherlands)
Sax Liao, ASML Netherlands B.V. (Netherlands)
Ken Chang, ASML Netherlands B.V. (Netherlands)
Vincent Couraudon, ASML Netherlands B.V. (Netherlands)
Eason Su, ASML Netherlands B.V. (Netherlands)
Wilson Tzeng, ASML Netherlands B.V. (Netherlands)
Cathy Wang, ASML Netherlands B.V. (Netherlands)
Christophe Fouquet, ASML Netherlands B.V. (Netherlands)
Guo-Tsai Huang, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
Kai-Hsiung Chen, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
Y. C. Wang, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
Kevin Cheng, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
Chih-Ming Ke, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
L. G. Terng, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)

Published in SPIE Proceedings Vol. 10145:
Metrology, Inspection, and Process Control for Microlithography XXXI
Martha I. Sanchez, Editor(s)

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