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Journal of Micro/Nanolithography, MEMS, and MOEMS • Open Access

Techniques for improving overlay accuracy by using device correlated metrology targets as reference
Author(s): Wei Jhe Tzai; Simon C. C. Hsu; Howard Chen; Charlie Chen; Yuan Chi Pai; Chun-Chi Yu; Chia-Ching Lin; Tal Itzkovich; Lipkong Yap; Eran Amit; David Tien; Eros Huang; Kelly T. L. Kuo; Nuriel Amir

Paper Abstract

The performance of overlay metrology as total measurement uncertainty, design rule compatibility, device correlation, and measurement accuracy has been challenged at the nm node and below. The process impact on overlay metrology is becoming critical, and techniques to improve measurement accuracy become increasingly important. We present a methodology for improving the overlay accuracy. A propriety quality metric, Qmerit, is used to identify overlay metrology measurement settings with the least process impacts and reliable accuracies. Using the quality metric, a calibration method, Archer self-calibration, is then used to remove the inaccuracies. Accuracy validation can be achieved by correlation to reference overlay data from another independent metrology source such as critical dimension–scanning electron microscopy data collected on a device correlated metrology hybrid target or by electrical testing. Additionally, reference metrology can also be used to verify which measurement conditions are the most accurate. We provide an example of such a case.

Paper Details

Date Published: 2 December 2014
PDF: 6 pages
J. Micro/Nanolith. MEMS MOEMS 13(4) 041412 doi: 10.1117/1.JMM.13.4.041412
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 13, Issue 4
Show Author Affiliations
Wei Jhe Tzai, United Microelectronics Corp. (Taiwan)
Simon C. C. Hsu, United Microelectronics Corp. (Taiwan)
Howard Chen, United Microelectronics Corp. (Taiwan)
Charlie Chen, United Microelectronics Corp. (Taiwan)
Yuan Chi Pai, United Microelectronics Corp. (Taiwan)
Chun-Chi Yu, United Microelectronics Corp. (Taiwan)
Chia-Ching Lin, United Microelectronics Corp. (Taiwan)
Tal Itzkovich, KLA-Tencor Israel (Israel)
Lipkong Yap, KLA-Tencor Corp. (United States)
Eran Amit, KLA-Tencor Israel (Israel)
David Tien, KLA-Tencor Corp. (United States)
Eros Huang, KLA-Tencor Taiwan (Taiwan)
Kelly T. L. Kuo, KLA-Tencor Taiwan (Taiwan)
Nuriel Amir, KLA-Tencor Israel (Israel)

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