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Proceedings Paper

Differential signal scatterometry overlay metrology: an accuracy investigation
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Paper Abstract

The overlay control budget for the 32nm technology node will be 5.7nm according to the ITRS. The overlay metrology budget is typically 1/10 of the overlay control budget resulting in overlay metrology total measurement uncertainty (TMU) requirements of 0.57nm for the most challenging use cases of the 32nm node. The current state of the art imaging overlay metrology technology does not meet this strict requirement, and further technology development is required to bring it to this level. In this work we present results of a study of an alternative technology for overlay metrology - Differential signal scatterometry overlay (SCOL). Theoretical considerations show that overlay technology based on differential signal scatterometry has inherent advantages, which will allow it to achieve the 32nm technology node requirements and go beyond it. We present results of simulations of the expected accuracy associated with a variety of scatterometry overlay target designs. We also present our first experimental results of scatterometry overlay measurements, comparing this technology with the standard imaging overlay metrology technology. In particular, we present performance results (precision and tool induced shift) and address the issue of accuracy of scatterometry overlay. We show that with the appropriate target design and algorithms scatterometry overlay achieves the accuracy required for future technology nodes.

Paper Details

Date Published: 18 June 2007
PDF: 11 pages
Proc. SPIE 6616, Optical Measurement Systems for Industrial Inspection V, 66160H (18 June 2007); doi: 10.1117/12.725929
Show Author Affiliations
Daniel Kandel, KLA-Tencor Corp. (Israel)
Mike Adel, KLA-Tencor Corp. (Israel)
Berta Dinu, KLA-Tencor Corp. (Israel)
Boris Golovanevsky, KLA-Tencor Corp. (Israel)
Pavel Izikson, KLA-Tencor Corp. (Israel)
Vladimir Levinski, KLA-Tencor Corp. (Israel)
Irina Vakshtein, KLA-Tencor Corp. (Israel)
Philippe Leray, IMEC (Belgium)
Mauro Vasconi, STMicroelectronics (Italy)
Bartlomiej Salski, QWED Sp. z.o.o. (Poland)

Published in SPIE Proceedings Vol. 6616:
Optical Measurement Systems for Industrial Inspection V
Wolfgang Osten; Christophe Gorecki; Erik L. Novak, Editor(s)

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