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Proceedings Paper

Diffraction-based overlay measurement on dedicated mark using rigorous modeling method
Author(s): Hailiang Lu; Fan Wang; Qingyun Zhang; Yonghui Chen; Chang Zhou
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Paper Abstract

Diffraction Based Overlay (DBO) is widely evaluated by numerous authors, results show DBO can provide better performance than Imaging Based Overlay (IBO). However, DBO has its own problems. As well known, Modeling based DBO (mDBO) faces challenges of low measurement sensitivity and crosstalk between various structure parameters, which may result in poor accuracy and precision. Meanwhile, main obstacle encountered by empirical DBO (eDBO) is that a few pads must be employed to gain sufficient information on overlay-induced diffraction signature variations, which consumes more wafer space and costs more measuring time. Also, eDBO may suffer from mark profile asymmetry caused by processes. In this paper, we propose an alternative DBO technology that employs a dedicated overlay mark and takes a rigorous modeling approach. This technology needs only two or three pads for each direction, which is economic and time saving. While overlay measurement error induced by mark profile asymmetry being reduced, this technology is expected to be as accurate and precise as scatterometry technologies.

Paper Details

Date Published: 5 April 2012
PDF: 7 pages
Proc. SPIE 8324, Metrology, Inspection, and Process Control for Microlithography XXVI, 832422 (5 April 2012); doi: 10.1117/12.916365
Show Author Affiliations
Hailiang Lu, Shanghai Micro Electronics Equipment Co., Ltd. (China)
Fan Wang, Shanghai Micro Electronics Equipment Co., Ltd. (China)
Qingyun Zhang, Shanghai Micro Electronics Equipment Co., Ltd. (China)
Yonghui Chen, Shanghai Micro Electronics Equipment Co., Ltd. (China)
Chang Zhou, Shanghai Micro Electronics Equipment Co., Ltd. (China)


Published in SPIE Proceedings Vol. 8324:
Metrology, Inspection, and Process Control for Microlithography XXVI
Alexander Starikov, Editor(s)

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