Robust edge detection with considering three-dimensional sidewall feature by CD-SEM

A. Yamaguchi; H. Koyanagi; J. Tanaka; O. Inoue; H. Kawada

doi:10.1117/12.881194

28 March 2011 Robust edge detection with considering three-dimensional sidewall feature by CD-SEM

A. Yamaguchi, H. Koyanagi, J. Tanaka, O. Inoue, H. Kawada

Proceedings Volume 7971, Metrology, Inspection, and Process Control for Microlithography XXV; 79710A (2011) https://doi.org/10.1117/12.881194
Event: SPIE Advanced Lithography, 2011, San Jose, California, United States

Abstract

A method for achieving high repeatability in edge detection considering a three-dimensional (3D) feature of a pattern sidewall was developed. An edge-detection condition is regarded as the metric representing the z-coordinate (height) of the edge position. The dependences of line-edge or linewidth roughness (LER/LWR) and LER/LWR bias on the edgedetection condition were calculated. The calculated dependence is interpreted as the qualitative z-dependence of the roughness metrics. The 3D feature of the sidewall can therefore be roughly estimated from the dependence. The condition that minimizes the LER/LWR bias to achieve high repeatability for local measurements was determined. First, to check the validity of this method, the feasibility of 3D information extraction was examined. Unbiased LER and LER bias of resist and silicon pattern samples were plotted against the edge-detection condition, and it was found that the characteristics of the graphs of the unbiased LER and bias are related to the 3D feature observed by atomic force microscopy. Next, the robustness of the method against a change in the pattern shape caused by exposure defocus was demonstrated. Finally, it was shown that the method actually improves local measurement repeatability. In the case of the linewidth of a 9-nm-long line, repeatability was improved by 40% compared with that under the conventional edgedetection condition.

Citation Download Citation

A. Yamaguchi, H. Koyanagi, J. Tanaka, O. Inoue, and H. Kawada "Robust edge detection with considering three-dimensional sidewall feature by CD-SEM", Proc. SPIE 7971, Metrology, Inspection, and Process Control for Microlithography XXV, 79710A (28 March 2011); https://doi.org/10.1117/12.881194

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