Accurate vertical sidewall measurement by a metrological tilting-AFM for reference metrology of line edge roughness

Ryosuke Kizu; Ichiko Misumi; Akiko Hirai; Satoshi Gonda

doi:10.1117/12.2511712

26 March 2019 Accurate vertical sidewall measurement by a metrological tilting-AFM for reference metrology of line edge roughness

Ryosuke Kizu, Ichiko Misumi, Akiko Hirai, Satoshi Gonda

Author Affiliations +

Proceedings Volume 10959, Metrology, Inspection, and Process Control for Microlithography XXXIII; 109592B (2019) https://doi.org/10.1117/12.2511712
Event: SPIE Advanced Lithography, 2019, San Jose, California, United States

Abstract

Line edge roughness (LER) measurement is one of the metrology challenges for 3D device structures, and LER reference metrology is important for reliable LER measurements. We developed an LER measurement technique, which is able to analyze LER distribution along height of a line pattern, with high accuracy, resolution, and reproducibility. Highly accurate atomic force microscopy (AFM) image of a vertical sidewall of a line pattern was obtained using a metrological tilting- AFM, which offers SI-traceable dimensional measurements. The tilting-tip was controlled with an inclined servo axis and scans the vertical sidewall along a line pattern with a high sampling density to enable an analysis of the LER height distribution at the sidewall. A horizontal cross-section of the sidewall shows sidewall roughness with sub-nm resolution. Power spectral density (PSD) analysis of the sidewall profile showed that the PSD noise in the high-frequency region was several orders of magnitude lower than the noise of typical scanning electron microscopy methods. AFM measurements were sequentially repeated three times to evaluate the reproducibility of the sidewall measurement and LER analysis; results indicated a high reproducibility of 0.07 nm evaluated as a standard deviation of LER at each height.

Citation Download Citation

Ryosuke Kizu, Ichiko Misumi, Akiko Hirai, and Satoshi Gonda "Accurate vertical sidewall measurement by a metrological tilting-AFM for reference metrology of line edge roughness", Proc. SPIE 10959, Metrology, Inspection, and Process Control for Microlithography XXXIII, 109592B (26 March 2019); https://doi.org/10.1117/12.2511712

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