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Proceedings Paper

Influence of image processing on line-edge roughness in CD-SEM measurement
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Paper Abstract

The necessity for and validity of the bias-free line-edge roughness (LER) evaluation are examined. In a typical case, the LER obtained by the conventional method is found to contain 10% or more bias caused by noise. That is, the biasfree LER evaluation is needed to achieve absolute measurements. The bias-free method is also shown to be necessary in relative LER measurements. Moreover, the impact of the smoothing (i.e., averaging the signal intensity in x-direction) process on the LER obtained from scanning electron microscope (SEM) image was evaluated quantitatively by using the bias-free LER evaluation algorithm. We found that the smoothing broadens the SEM signal profile and causes a change in the LER value. Under practical conditions, his smoothing-induced LER change was 0.4 nm in the sample used for this study. This can be a large error when measuring a small LER. Finally, a procedure for optimizing the smoothing number used for applying the bias-free LER application was proposed by considering the validity limit of the application and smoothing-induced LER change.

Paper Details

Date Published: 24 March 2008
PDF: 8 pages
Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 692221 (24 March 2008); doi: 10.1117/12.775664
Show Author Affiliations
Atsuko Yamaguchi, Hitachi, Ltd. (Japan)
Jiro Yamamoto, Hitachi, Ltd. (Japan)


Published in SPIE Proceedings Vol. 6922:
Metrology, Inspection, and Process Control for Microlithography XXII
John A. Allgair; Christopher J. Raymond, Editor(s)

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