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Does your SEM really tell the truth? How would you know? Part 2

Authors

  • Michael T. Postek,

    Corresponding author
    1. Semiconductor and Dimensional Metrology Division, Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland
    • Address for reprints: Michael T. Postek, Semiconductor and Dimensional Metrology Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899

      E-mail: postek@nist.gov

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  • András E. Vladár,

    1. Semiconductor and Dimensional Metrology Division, Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland
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  • Kavuri P. Purushotham

    1. Semiconductor and Dimensional Metrology Division, Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland
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  • 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.

Summary

The scanning electron microscope (SEM) has gone through a tremendous evolution to become indispensable for many and diverse scientific and industrial applications. The improvements have significantly enriched and augmented the overall SEM performance and have made the instrument far easier to operate. But, the ease of operation also might lead, through operator complacency, to poor results. In addition, the user friendliness has seemingly reduced the need for thorough operator training for using these complex instruments. One might then conclude that the SEM is just a very expensive digital camera or another peripheral device for a computer. Hence, a person using the instrument may be lulled into thinking that all of the potential pitfalls have been eliminated and they believe everything they see on the micrograph is always correct. But, this may not be the case. An earlier paper (Part 1), discussed some of the potential issues related to signal generation in the SEM, instrument calibration, electron beam interactions and the need for physics-based modeling to understand the actual image formation mechanisms. All these were summed together in a discussion of how these issues effect measurements made with the instrument. This second paper discusses another major issue confronting the microscopist: electron-beam-induced specimen contamination. Over the years, NIST has done a great deal of research into the issue of sample contamination and its removal and elimination and some of this work is reviewed and discussed here. SCANNING 36:347–355, 2014. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

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