SEM imaging of high aspect ratio trench by selectively controlling the electron beam irradiation using photocathode

Yuta Arakawa; Kotaro Niimi; Yohei Otsuka; Daiki Sato; Atsushi Koizumi; Haruka Shikano; Hokuto Iijima; Tomohiro Nishitani; Yoshio Honda; Hiroshi Amano

doi:10.1117/12.3010733

9 April 2024 SEM imaging of high aspect ratio trench by selectively controlling the electron beam irradiation using photocathode

Yuta Arakawa, Kotaro Niimi, Yohei Otsuka, Daiki Sato, Atsushi Koizumi, Haruka Shikano, Hokuto Iijima, Tomohiro Nishitani, Yoshio Honda, Hiroshi Amano

Author Affiliations +

Proceedings Volume 12955, Metrology, Inspection, and Process Control XXXVIII; 1295534 (2024) https://doi.org/10.1117/12.3010733
Event: SPIE Advanced Lithography + Patterning, 2024, San Jose, California, United States

Conference Poster

Abstract

Observation of high aspect ratio (HAR) structures is a difficult challenge in metrology and inspection in semiconductor manufacturing. In imaging HAR trenches using a scanning electron microscope (SEM), obtaining SEM images without information loss due to whiteouts and blackouts is challenging. One reason for the difficulty is that the probe current is constant in conventional SEM imaging. Suppose the probe current is increased to detect more secondary electrons from the bottom of the trench. In that case, excessive secondary electron emission from the top of the trench will result in a whiteout. The SEM equipped with a photocathode electron gun (PC-SEM) can change the probe current on a pixel-by-pixel basis by applying a pulsed electron beam. In this study, we propose two methods of SEM observation for HAR trenches. The first method uses a lower probe current at the top of the trench and a higher probe current at the bottom. With this method, the top and bottom of the trench could be observed simultaneously without any whiteout or blackout. Another method is to adjust the probe current so that the SEM image is in a constant grayscale. In this case, information about the sample appears in the probe current. The image of the probe current captured the trench bottom more clearly than the conventional SEM image under equivalent conditions.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

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Yuta Arakawa, Kotaro Niimi, Yohei Otsuka, Daiki Sato, Atsushi Koizumi, Haruka Shikano, Hokuto Iijima, Tomohiro Nishitani, Yoshio Honda, and Hiroshi Amano "SEM imaging of high aspect ratio trench by selectively controlling the electron beam irradiation using photocathode", Proc. SPIE 12955, Metrology, Inspection, and Process Control XXXVIII, 1295534 (9 April 2024); https://doi.org/10.1117/12.3010733

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