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Proceedings Paper

Improved diffraction-based overlay metrology by use of two dimensional array target
Author(s): Yi-Sha Ku; Hsiu-Lan Pang; Weite Hsu; Deh-Ming Shyu
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Paper Abstract

We report results of theoretical modeling into a scatterometry-based method relevant to overlay measurement. A set of two array targets were designed with intentional offsets difference, d and d+20 nm, between the top and bottom grid arrays along the X and Y directions. The correlation of bi-azimuth measurements is the first critical issue been taken into account. The method linearizes the differential values of scatterometry signatures at the first diffraction order with respect to designed offsets, and hence permits determination of overlay using a classical linear method. By evaluating the process variations (eg. CD, roundness and thickness) on overlay measurement error, a set of two overlay target design were optimized to minimize the correlation of bi-azimuth measurements and maximize the measurement sensitivity.

Paper Details

Date Published: 21 August 2009
PDF: 9 pages
Proc. SPIE 7405, Instrumentation, Metrology, and Standards for Nanomanufacturing III, 74050C (21 August 2009); doi: 10.1117/12.825524
Show Author Affiliations
Yi-Sha Ku, Industrial Technology Research Institute (Taiwan)
Hsiu-Lan Pang, Industrial Technology Research Institute (Taiwan)
Weite Hsu, Industrial Technology Research Institute (Taiwan)
Deh-Ming Shyu, Industrial Technology Research Institute (Taiwan)

Published in SPIE Proceedings Vol. 7405:
Instrumentation, Metrology, and Standards for Nanomanufacturing III
Michael T. Postek; John A. Allgair, Editor(s)

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