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Investigation of the Image Contrast in an Ultra-Low Voltage Scanning Electron Microscope Using an Auger Electron Spectrometer

Published online by Cambridge University Press:  22 November 2019

Yusuke Sakuda ,
Shunsuke Asahina ,
Takanari Togashi ,
Osamu Terasaki  and
Masato Kurihara
Yusuke Sakuda
Affiliation:
JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo196-8558, Japan Yamagata University, 1-4-12, Kojirakawamachi, Yamagata990-0021, Japan
Shunsuke Asahina*
Affiliation:
JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo196-8558, Japan
Takanari Togashi
Affiliation:
Yamagata University, 1-4-12, Kojirakawamachi, Yamagata990-0021, Japan
Osamu Terasaki
Affiliation:
Shanghai Tech University, 393 Middle Huaxia Road, Pudong, Shanghai201210, China
Masato Kurihara
Affiliation:
Yamagata University, 1-4-12, Kojirakawamachi, Yamagata990-0021, Japan
*
*Author for correspondence: Shunsuke Asahina, E-mail: sasahina@jeol.co.jp
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Abstract

Surface-sensitive information on a bulk sample can be obtained by using a low incident electron energy (low accelerating voltage/landing voltage) in a scanning electron microscope (SEM). However, topography and composition contrast obtained at low incident electron energies may not be intuitive and should be analyzed carefully. By combining an Auger electron spectrometer (AES) with a low incident electron energy SEM (LE-SEM), we investigated the SEM contrast carefully by separating the secondary electron (SE) and back-scattered electron (BSE) components with high accuracy. For this, we modified an AES to measure the electron energy in the range of 0–0.6 keV with a sample bias voltage of 0 to −0.3 keV. We could clearly observe reversed brightness of gold and carbon (graphite) in BSE images when the energy of the incident electrons was reduced to 0.2–0.3 keV. In addition, reflected electron energy spectroscopy (REELS) is known to be a tool for chemical state analysis of the sample. We demonstrated that it is possible to study the electron states of graphite, diamond, and graphene by acquiring low incident energy REELS spectra from their surfaces with the newly modified AES. This will be a new method for analyzing the electron states of local areas of a surface.

Keywords

Auger electron spectroscopyback-scattered electron imagereflected electron energy spectroscopyscanning electron microscope
Type
Australian Microbeam Analysis Society Special Section AMAS XV 2019
Information
Microscopy and Microanalysis , Volume 26 , Issue 4 , August 2020 , pp. 758 - 767
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Copyright
Copyright © Microscopy Society of America 2019

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