Quality improvement of environmental secondary electron detector signal using helium gas in variable pressure scanning electron microscopy |
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Authors: | Oho Eisaku Suzuki Kazuhiko Yamazaki Sadao |
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Affiliation: | Department of Electrical Engineering, Kogakuin University, Tokyo, Japan. oho@cc.kogakuin.ac.jp |
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Abstract: | The quality of the image signal obtained from the environmental secondary electron detector (ESED) employed in a variable pressure (VP) SEM can be dramatically improved by using helium gas. The signal-to-noise ratio (SNR) increases gradually in the range of the pressures that can be used in our modified SEM. This method is especially useful in low-voltage VP SEM as well as in a variety of SEM operating conditions, because helium gas can more or less maintain the amount of unscattered primary electrons. In order to measure the SNR precisely, a digital scan generator system for obtaining two images with identical views is employed as a precondition. |
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Keywords: | environmental secondary electron detector (ESED) low voltage variable pressure helium gas signal‐to‐noise ratio |
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