Contamination in a scanning electron microscope and the influence of specimen cooling

Hirsch, P. B.; Kässens, Manfred; Püttmann, M.; Reimer, Ludwig

doi:10.1002/sca.4950160207

Cited by 66 publications

(44 citation statements)

References 19 publications

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“…The initial temperature drop using LN2 is rapid, with the cold 119 finger quickly passing from 20°C to -50°C (see Figure 3a) preventing contaminate precipitation 120 keeping pace with temperature change. Given this, -27°C is a more accurate estimate of the 121 minimum temperature required for effective anticontamination, which is consistent with the 122 previous work by Hirsch et al (1994) and comparable to that of Heide (1963) It is unclear whether the carbon coat has an effect on the contamination rate or the temperature at 134 which minimum contamination is observed. However, the data shows a close agreement with that of 135 Hirsch et al (1994) for uncoated polished copper.…”

supporting

confidence: 81%

Decontamination in the Electron Probe Microanalysis with a Peltier-Cooled Cold Finger

et al. 2016

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A prototype Peltier thermoelectric cooling unit has been constructed to cool a cold finger on an electron microprobe. The Peltier unit was tested at 15 and 96 W, achieving cold finger temperatures of −10 and −27°C, respectively. The Peltier unit did not adversely affect the analytical stability of the instrument. Heat conduction between the Peltier unit mounted outside the vacuum and the cold finger was found to be very efficient. Under Peltier cooling, the vacuum improvement associated with water vapor deposition was not achieved; this has the advantage of avoiding severe degradation of the vacuum observed when warming up a cold finger from liquid nitrogen (LN2) temperatures. Carbon contamination rates were reduced as cooling commenced; by −27°C contamination rates were found to be comparable with LN2-cooled devices. Peltier cooling, therefore, provides a viable alternative to LN2-cooled cold fingers, with few of their associated disadvantages.

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confidence: 81%

Decontamination in the Electron Probe Microanalysis with a Peltier-Cooled Cold Finger

et al. 2016

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“…The typical analysis of the HOPG is carried out on the top layer at a distance from the edge but any existing contamination within the graphite gallery or on the underlayers while not visible could affect the response of the material to the electron beam. Investigations at cryoconditions are often used to reduce the contamination issue, Figure b,c show cryo‐LV SEM micrographs of HOPG at low and high magnification respectively. Contamination islands can still be observed across the whole of the surface on the fresh surface, they are seen on all the typical topographical features of HOPG such as steps (highlighted by orange arrows), terraces (highlighted by green arrows) and folds (highlighted by brown arrows.…”

Section: Resultsmentioning

confidence: 99%

Making Sense of Complex Carbon and Metal/Carbon Systems by Secondary Electron Hyperspectral Imaging

et al. 2019

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Carbon and carbon/metal systems with a multitude of functionalities are ubiquitous in new technologies but understanding on the nanoscale remains elusive due to their affinity for interaction with their environment and limitations in available characterization techniques. This paper introduces a spectroscopic technique and demonstrates its capacity to reveal chemical variations of carbon. The effectiveness of this approach is validated experimentally through spatially averaging spectroscopic techniques and using Monte Carlo modeling. Characteristic spectra shapes and peak positions for varying contributions of sp2‐like or sp3‐like bond types and amorphous hydrogenated carbon are reported under circumstances which might be observed on highly oriented pyrolytic graphite (HOPG) surfaces as a result of air or electron beam exposure. The spectral features identified above are then used to identify the different forms of carbon present within the metallic films deposited from reactive organometallic inks. While spectra for metals is obtained in dedicated surface science instrumentation, the complex relations between carbon and metal species is only revealed by secondary electron (SE) spectroscopy and SE hyperspectral imaging obtained in a state‐of‐the‐art scanning electron microscope (SEM). This work reveals the inhomogeneous incorporation of carbon on the nanoscale but also uncovers a link between local orientation of metallic components and carbon form.

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“…Several published studies (Black, ; Harada et al ., ; Hren, ; Akishige, ; Hirsch et al ., ; Bruenger et al ., ) documented well that the origins of the contamination are both the sample itself and the vacuum system of the SEM. Although the pumping system is a major contributor to this problem, the history of the specimen prior to entering the vacuum system is also important.…”

Section: Charged Beam‐induced Sample Contaminationmentioning

confidence: 98%

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

Postek

Vladár

2013

Scanning

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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.

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Contamination in a scanning electron microscope and the influence of specimen cooling

Cited by 66 publications

References 19 publications

Decontamination in the Electron Probe Microanalysis with a Peltier-Cooled Cold Finger

Decontamination in the Electron Probe Microanalysis with a Peltier-Cooled Cold Finger

Making Sense of Complex Carbon and Metal/Carbon Systems by Secondary Electron Hyperspectral Imaging

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

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