Does your SEM really tell the truth? How would you know? part 3: vibration and drift

Abstract

This is the third of a series of papers discussing various causes of measurement uncertainty in scanned particle beam instruments, and some of the solutions researched and developed at NIST. Scanned particle beam instruments especially the scanning electron microscope (SEM) have gone through tremendous evolution to become indispensable tools for many and diverse scientifi c and industrial applications. These improvements have signifi cantly enhanced their performance and made them far easier to operate. But, ease of operation has also fostered operator complacency. In addition, the user-friendliness has reduced the need for extensive operator training. Unfortunately, this has led to the concept that the SEM is just another expensive digital camera or another peripheral device connected to a computer and that all of the issues related to obtaining quality data have been solved. Hence, a person (or company) using these instruments may be lulled into thinking that all of the potential pitfalls have been fully eliminated and they believe everything they see on the micrograph is always correct. But, as described in this and the earlier presentations this may not be the case. The fi rst paper in this series discussed some of the issues related to signal generation in the SEM, including instrument calibration, electron beam-sample interactions and the need for physics-based modelling to understand the actual image formation mechanisms to properly interpret SEM images. The second paper, discussed another major issue confronting the microscopist: specimen contamination and methods of contamination elimination. This third paper, discusses vibration and drift and some useful solutions. INTRODUCTIONScanning electron microscopes are used extensively in nanomanufacturing characterization, metrology and process control. Two earlier papers (1, 2), discussed some of the potential issues related to signal generation in the SEM, instrument calibration, electron beam interactions, and the need for modelling to understand the actual image generation. All these were summed together in a discussion of how these issues effect measurements made with the instrument. The second paper, discussed another major issue confronting the microscopist: which is specimen contamination and methods of contamination reduction and elimination. This third paper, discusses the additional components of measurement uncertainty induced by vibration and drift and some possible solutions to these issues. Over the years, several workers at NIST have done a great deal of research into these issues in order to improve the fundamental metrology with particle beam instruments and some of this work is reviewed and discussed here.

Improving robustness for model discerning synthesis process of uranium oxide with unsupervised domain adaptation

“…(Please refer to the web version for the interpretation of the references to color). caused by uncalibrated microscope, the drift of the stage during an acquisition, electron beam-induced contamination, and others Postek et al, 2014;Postek and Vladár, 2015) is another directly related follow-up work that also needs to be addressed. These pitfalls present a much more challenging problem, and are also commonly encountered in realworld scenarios.…”

Information or resolution: Which is required from an SEM to study bulk inorganic materials?

“…Installation environment factors including stray electromagnetic fields, vibration, acoustic noise, and variations in room temperature and chilling water temperature (if the SEM is water chilled), can have large effects on practical performance (Postek et al ., ). In reality, many SEMs are not housed in the buildings specifically designed to minimize the influences from the above environmental factors.…”