UV Treatment of TEM/STEM Samples for Reduced Hydrocarbon Contamination

Hoyle, David; Malac, Marek; Trudeau, M.; Woo, Patrick

doi:10.1017/s1431927611006003

Cited by 13 publications

(8 citation statements)

References 2 publications

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“…Short wavelength ultra-violet light (UV A) and ozone have been used to remove hydrocarbons from surfaces, and a commercial system designed for TEM specimen cleaning is available (Hoyle et al, 2011). We do not have access to such a TEM specimen cleaner, but instead used a Bioforce Nanosciences UV/Ozone Procleaner system.…”

Section: The Effect Of Uv/ozone Cleaningmentioning

confidence: 99%

“…Strategies for dealing with contamination have been developed, and include plasma cleaning (Griffiths A. J. V., 2010;Isabell et al, 1999;McGilvery et al, 2012;Zaluzec, 2001;Zaluzec et al, 1997), baking (Egerton et al, 2004;McGilvery et al, 2012;Soong et al, 2012;Williams and Carter, 1996), exposure to ultraviolet light and ozone (Hoyle et al, 2011;Soong et al, 2012) , cooling (Egerton and Rossouw, 1976;Hren, 1986) and beam showering (Egerton et al, 2004). The need for such contamination mitigation strategies has been made even more pressing with the advent aberration corrected STEM.…”

Section: Introductionmentioning

confidence: 99%

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Contamination mitigation strategies for scanning transmission electron microscopy

Mitchell

2015

Micron

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Modern scanning transmission electron microscopy (STEM) enables imaging and microanalysis at very high magnification. In the case of aberration-corrected STEM, atomic resolution is readily achieved. However, the electron fluxes used may be up to three orders of magnitude greater than those typically employed in conventional STEM. Since specimen contamination often increases with electron flux, specimen cleanliness is a critical factor in obtaining meaningful data when carrying out high magnification STEM. A range of different specimen cleaning methods have been applied to a variety of specimen types. The contamination rate has been measured quantitatively to assess the effectiveness of cleaning. The methods studied include: baking, cooling, plasma cleaning, beam showering and UV/ozone exposure. Of the methods tested, beam showering is rapid, experimentally convenient and very effective on a wide range of specimens. Oxidative plasma cleaning is also very effective and can be applied to specimens on carbon support films, albeit with some care. For electron beam-sensitive materials, cooling may be the method of choice. In most cases, preliminary removal of the bulk of the contamination by methods such as baking or plasma cleaning, followed by beam showering, where necessary, can result in a contamination-free specimen suitable for extended atomic scale imaging and analysis. Modern scanning transmission electron microscopy (STEM) enables imaging and microanalysis at very high magnification. In the case of aberration-corrected STEM, atomic resolution is readily achieved. However, the electron fluxes used may be up to three orders of magnitude greater than those typically employed in conventional STEM. Since specimen contamination often increases with electron flux, specimen cleanliness is a critical factor in obtaining meaningful data when carrying out high magnification STEM. A range of different specimen cleaning methods have been applied to a variety of specimen types. The contamination rate has been measured quantitatively to assess the effectiveness of cleaning. The methods studied include: baking, cooling, plasma cleaning, beam showering and UV/ozone exposure. Of the methods tested, beam showering is rapid, experimentally convenient and very effective on a wide range of specimens. Oxidative plasma cleaning is also very effective and can be applied to specimens on carbon support films, albeit with some care. For electron beam-sensitive materials, cooling may be the method of choice. In most cases, preliminary removal of the bulk of the contamination by methods such as baking or plasma cleaning, followed by beam showering, where necessary, can result in a contamination-free specimen suitable for extended atomic scale imaging and analysis.

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Section: The Effect Of Uv/ozone Cleaningmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Contamination mitigation strategies for scanning transmission electron microscopy

Mitchell

2015

Micron

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“…All specimens were cleaned, prior to observation, with a Hitachi ZoneSEM (Hitachi High Technologies) ozone cleaner to remove the remaining hydrocarbons from the surface of the specimens to avoid carbon contamination under the electron beam (Hoyle et al, 2011; Soong et al, 2012). The specimen was positioned at 3 mm from the ultra-violet lamp and cleaned for 10 min under an ozone atmosphere of 227 torrs.…”

Section: Methodsmentioning

confidence: 99%

Dark-Field Imaging of Thin Specimens with a Forescatter Electron Detector at Low Accelerating Voltage

2013

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A forescatter electron detector (FSED) was used to acquire dark-field micrographs (DF-FSED) on thin specimens with a scanning electron microscope. The collection angles were adjusted with the detector distance from the beam axis, which is similar to the camera length of the scanning transmission electron microscope annular DF detectors. The DF-FSED imaging resolution was calculated with SMART-J on an aluminum alloy and carbon nanotubes (CNTs) decorated with platinum nanoparticles. The resolution was three to six times worse than with bright-field imaging. Measurements of nanometer-size objects showed a similar feature size in DF-FSED imaging despite a signal-to-noise ratio 12 times smaller. Monte Carlo simulations were used to predict the variation of the contrast of a CNT/Fe/Pt system as a function of the collection angles. It was constant for very high collection angles (>450 mrad) and confirmed experimentally. The reverse contrast between carbon black particles and the smallest titanium dioxide (TiO2) nanoparticles was predicted by Monte Carlo simulations and observed in the DF-FSED micrograph of a battery electrode coating. However, segmentation of the micrograph was not able to isolate the TiO2 nanoparticle phase because of the close contrast of small TiO2 nanoparticles compared to the C black particles.

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“…Depositing an unknown amount of electron beam-induced carbonaceous contamination while measuring the sample hampers or prevents the collection of reliable information. Fortunately, there are known solutions for this problem: by introducing low-energy oxygen, hydrogen or helium plasma or UV light 86 and employing good sample preparation and handling practices, it is possible to achieve such cleanliness that even hours of continuous electron beam exposure will not deposit any noticeable contamination. 87,88 For many types of e-beam measurements ultra-high cleanliness is sufficient, but for some (e.g.…”

Section: Contamination Damage and Chargingmentioning

confidence: 99%

Research Update: Electron beam-based metrology after CMOS

et al. 2018

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The magnitudes of the challenges facing electron-based metrology for post-CMOS technology are reviewed. Directed selfassembly, nanophotonics/plasmonics, and resistive switches and selectors, are examined as exemplars of important post-CMOS technologies. Materials, devices, and architectures emerging from these technologies pose new metrology requirements: defect detection, possibly subsurface, in soft materials, accurate measurement of size, shape, and roughness of structures for nanophotonic devices, contamination-free measurement of surface-sensitive structures, and identification of subtle structural, chemical, or electronic changes of state associated with switching in non-volatile memory elements. Electron-beam techniques are examined in the light of these emerging requirements. The strong electron-matter interaction provides measurable signal from small sample features, rendering electron-beam methods more suitable than most for nanometer-scale metrology, but as is to be expected, solutions to many of the measurement challenges are yet to be demonstrated. The seeds of possible solutions are identified when they are available.

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UV Treatment of TEM/STEM Samples for Reduced Hydrocarbon Contamination

Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Cited by 13 publications

References 2 publications

Contamination mitigation strategies for scanning transmission electron microscopy

Contamination mitigation strategies for scanning transmission electron microscopy

Dark-Field Imaging of Thin Specimens with a Forescatter Electron Detector at Low Accelerating Voltage

Research Update: Electron beam-based metrology after CMOS

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