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On the Sub-Nanometer Resolution of Scanning Electron and Helium Ion Microscopes

Published online by Cambridge University Press:  14 March 2018

András E. Vladár*
Affiliation:
National Institute of Standards and Technology (NIST)1, Gaithersburg, MD 20899-8212
Michael T. Postek
Affiliation:
National Institute of Standards and Technology (NIST)1, Gaithersburg, MD 20899-8212
Bin Ming
Affiliation:
National Institute of Standards and Technology (NIST)1, Gaithersburg, MD 20899-8212

Extract

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All forms of microscopy are being pushed to the limit by nanotechnology. This is especially true for high-resolution scanning electron and helium ion microscopes, which are proving to be extremely useful for nanometer-scale imaging, characterization, and dimensional measurements. Excellent resolution is essential for imaging nanomaterials. Hence, there is a relentless quest to achieve better and better resolution with various electron and ion microscopes and to monitor and maintain these instruments to achieve the best possible performance levels.

The ability to resolve fine details with a microscope has greatly improved over the past 20 years. The resolution achievable with the newest scanning electron microscopes (SEMs) can now be at or below 0.4 nm and for the scanning helium ion microscope (HeIM), 0.24 nm has been reported. To put this into perspective, the {111} crystal plane in silicon (Si) has 0.32 nm lattice spacing, so one cubic nanometer in the Si crystal contains only a few atoms. Therefore, an instrument must be performing at the highest level possible to resolve routinely the finest structures. Clearly, the instrument operator must also be functioning at a high level as well to achieve the best resolution and to prove that the instrument is capable of doing the work.

Type
Research Article
Copyright
Copyright © Microscopy Society of America 2009

Footnotes

1

Contribution of the National Institute of Standards and Technology; not subject to copyright. Certain commercial equipment is identified in this report to adequately describe the experimental procedure. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the equipment identified is necessarily the best available for the purpose.

References

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