Laser assisted SEM for visualizing electrical property using voltage contrast dynamics

Minami Shoji; Yohei Nakamura; Yasuhiro Shirasaki; Shota Mitsugi; Heita Kimizuka; Satoshi Takada; Yuko Iwabuchi; Natsuki Tsuno

doi:10.1117/12.2658182

27 April 2023 Laser assisted SEM for visualizing electrical property using voltage contrast dynamics

Minami Shoji, Yohei Nakamura, Yasuhiro Shirasaki, Shota Mitsugi, Heita Kimizuka, Satoshi Takada, Yuko Iwabuchi, Natsuki Tsuno

Author Affiliations +

Proceedings Volume 12496, Metrology, Inspection, and Process Control XXXVII; 1249630 (2023) https://doi.org/10.1117/12.2658182
Event: SPIE Advanced Lithography + Patterning, 2023, San Jose, California, United States

Conference Poster

Abstract

In addition to the conventional process control method like dimensional metrology, there is a growing need to measure the electrical characteristics of device structures. Detection of defective electrical characteristics during device fabrication is important to improve device yield and shorten the ramp-up time of the manufacturing process. Voltage contrast of traditional scanning electron microscopes can be used to measure some of the electrical characteristics but is limited in its sensitivity and, hence, its applicable processes. We have developed a Laser-assisted SEM (LA-SEM) with (1) laser irradiation function and (2) electron beam modulation function to control and enhance the voltage contrast (VC) for in-line electrical inspection and measurement. In this report, for samples with high-impedance components obstructing the view of defect of interest, we confirmed that ultraviolet laser irradiation provides defect contrast that cannot be obtained with electron-beam-only VC. For Not-Open defects on a PN junction, the VC was improved by a factor of 1.19 by using a laser in the near-infrared region. Furthermore, to extract electrical properties of defects and monitor their changes during the manufacturing flow, a VC circuit simulation function was developed to quantitatively estimate VC transients obtained by modulated electron beam irradiation. As an example, a quantitative estimation of RC by transient voltage contrast analysis was performed on floating plugs with varying resistance using metal film deposition on its side walls. A decent correlation between the estimated electrical properties and the sheet resistance of the metallic film was demonstrated.

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Minami Shoji, Yohei Nakamura, Yasuhiro Shirasaki, Shota Mitsugi, Heita Kimizuka, Satoshi Takada, Yuko Iwabuchi, and Natsuki Tsuno "Laser assisted SEM for visualizing electrical property using voltage contrast dynamics", Proc. SPIE 12496, Metrology, Inspection, and Process Control XXXVII, 1249630 (27 April 2023); https://doi.org/10.1117/12.2658182

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