The cleanliness of specimen surfaces and the high-vacuum electron microscope settings in which these surfaces are analyzed or treated has never been more important as inspection and manufacturing approach the atomic level.
Image Credit: XEI Scientific
Compact electron probes with large beam currents are required to achieve such precision. Routine production at the nanoscale requires immaculate and regulated surfaces to get the appropriate structures.
Modern electron and ion microscopes have sophisticated vacuum systems that can achieve these conditions, although maintaining cleanliness over time may be more difficult.
Scientists have used several plasma technologies to clean their samples and microscopes, which has helped them produce these astonishingly clean surfaces.
Hydrocarbon molecules from sample or vacuum chamber surfaces are an example of contamination. Small quantities can interact with the electron or ion beam, causing undesirable artifacts in images or data.1
Hydrocarbon contamination can occur from a variety of sources during specimen preparation, including inadvertent touching of the specimen or specimen holder or handing the samples without gloves, backstreaming if the microscope has an oil diffusion pump system, chemicals used during electrolytic thinning or layer removal, or adhesives or solvents used to fix the sample to the sample stub.
While contamination is frequently associated with examining non-biological samples, it is important to note that exposing biological and polymeric samples to ion and electron beams can result in extensive carbon contamination, and the tools used for this work are frequently in desperate need of cleaning methods.2
Carbon Contamination
The problem of hydrocarbon contamination inside the electron microscope is well established and has existed from the beginning of electron microscopy.3,4
This artifact is commonly caused by the electron (or ion) beam impacting undesirable contaminant molecules and stimulating the formation of carbonaceous compounds on the sample's surface.
Because of the lower amounts of energy, secondary electrons reach the detector from the contaminated surface, and the contamination zone frequently appears as a darkening area in the secondary electron image.
Typically, in a beam scanning instrument, this contaminated layer is in the shape of the raster pattern on the sample, a rectangle (Figure 1). The impact is more noticeable at high magnification and lower accelerating voltages, which are the typical circumstances for analyzing small surface details.
Cleaning the specimen before placing it in the scanning electron microscope (SEM) is beneficial, but there is always a trace of hydrocarbon in the system.
The source of these residual hydrocarbons is diverse. They can be left behind during tool manufacturing, as part of the vacuum or lubrication system, or as a result of sample handling, highlighting the need for periodic chamber cleaning.
Figure 1. Four contamination rectangles were created on a patterned silicon wafer sample by rastering the beam for 1, 2, 4, and 8 hours (left to right respectively) at 2 kV and a beam intensity of 18 in the MIRA3. To record this image a TESCAN MIRA3 Field-Emission SEM was equipped with an Evactron® E50 plasma cleaner, a SmarAct 8 axes piezo stage, and a multi-detector setup made by Pointelectronic. The thickness of the hydrocarbon deposition layer on the darkest rectangle on the right is ~1000 nm (Armbruster et al., 2019). Image Credit: XEI Scientific
Historical Background
In 1999, XEI Scientific developed the Evactron De-Contaminator, a viable plasma cleaning system for SEMs that could be mounted on the chamber to clean in situ.5
The original Evactron design employed a simple, manually operated micro-needle valve as a metering valve for the air entering the plasma radical source (PRS), which produced oxygen radicals.
This Evactron model featured a vacuum pump with a constant rotational speed, such as a rotary vane pump. The pressure could only be changed once during installation. When open, the leak valve and roughing pump always reached the same equilibrium pressure.
Newer SEM evacuation system designs have a turbo pump that accelerates during pump down. In 2004, a servo-controlled flow valve was added to an Evactron model to help maintain pressure. In 2008, the control logic was moved to a microprocessor, and time, power, and pressure were made programmable.
Evactron models were then developed to work under turbo pressures.2,6 Figure 2 illustrates some of these design innovations.
Figure 2. Three generations of Evactron plasma cleaners mounted on SEMs. 1) Evactron 10 plasma radical source in 2004 with the first servo control of pressure, 2) Evactron 25 plasma radical source with shroud over the valve manifold, and 3) Evactron E50 plasma radical source released in 2018 gives high-performance cleaning at 50 watts, has an external hollow cathode and lower cost. Image Credit: XEI Scientific
Plasma cleaners are ubiquitous in electron microscope suites, with users from several disciplines cleaning samples and sample holders before microscopy.7
Many manufacturers offer desktop plasma cleaners. These vary in sophistication and cost. However, these tools do not address the microscope's interior surfaces.
Although the amount of mobile hydrocarbon pollutants held by those interior surfaces may be insignificant, the scales at which observations are now being conducted necessitate an adequate resolution if progress is to be sustained.
Any proposed solution that requires component disassembly and manual cleaning is unlikely to be practical. Even if pursued, it would entail a level of manual intervention that could impose a disproportionate economic burden on any cost-benefit analysis for research.
Theory of Operation
The Evactron device creates plasma, which is converted into oxygen or hydrogen radicals to remove hydrocarbons from vacuum systems. Because the vacuum part of the Evactron, the PRS, generates remote plasma, the chamber and specimen are not directly exposed to plasma.
Figure 3 depicts the main premise that the plasma generates active species that convectively flow into the chamber and react with hydrocarbon pollutants, producing volatile chemicals that vacuum pumps may evacuate.
The system cleaning pressures are determined by the pumping system being used. If the system includes turbopumps, the chamber pressure typically ranges from 2 to 15 mTorr (0.3 to 2 Pa). If a roughing pump is used, the chamber pressures are typically between 200 and 400 mTorr (26 and 54 Pa).
Image Credit: XEI Scientific
Experiments with various gases to generate plasma have demonstrated that room air is an excellent supply of oxygen for producing reactive radicals and efficiently cracking hydrocarbon molecules.
It offers the advantages of being accessible, free, and secure. By using various noncorrosive gases to produce radicals, different chemical etch procedures can be employed. Benign regimes for delicate components and optimal chemistries for rapidly removing undesirable impurities can also be employed.
The Evactron cleaning procedure works because hydrocarbon oxidation products are volatile in a vacuum.
Oxygen radicals oxidize hydrocarbons, producing volatile oxides. Oxidation often begins with the scission of carbon-carbon bonds or hydride extraction (hydrogen atom removal), which generates reactive sites on the HC chain.
Subsequent interactions with oxygen radicals further degrade the chain, transforming hydrocarbons into short-chain ketones, alcohols, H2O, CO, and CO2, all easily pumped away.
Low pressures boost cleaning speeds by increasing mean free pathways and lowering oxygen radical recombination rates caused by three-body collisions.8 Residual gas analysis is useful for monitoring the elimination of contaminated species.9
The most thermodynamically advantageous processes include C double bond oxidation, hydride extraction, and C-C single bond oxidation. C-C single-bond oxidation is only modestly exothermic, which explains why polymers degrade much more slowly than single-chain HC compounds.
To form a reactive site, the C-C single bond is typically broken and oxidized following the oxidation of a neighboring bond. Fluorocarbons' C-F bond oxidation is extremely endothermic, and these compounds are non-reactive.
The target material's oxidation chemistry predicts how Evactron cleaning may affect other materials. If a stable oxide layer forms, as it does with most metals, electron plasma oxidation will cease.
The Evactron technology generates a distinct, low-temperature plasma for producing oxygen radicals from air. In air plasmas, oxygen is ionized and disassociated by a sequence of processes, creating oxygen radicals.
Unlike plasma ions, these radicals have a long lifetime and can depart the plasma excitation volume for later use. However, the radicals react with nitrogen ions in the plasma and are rapidly eliminated.
Because oxygen's ionization potential is 12.1 eV and nitrogen's is 15.6 eV, oxygen ionization is more likely in a low-temperature or low-energy plasma. The transition from an oxygen-dominated plasma to a nitrogen-dominated plasma is temperature-dependent.
Lowering the temperature of the electron energy distribution promotes oxygen ionization. When nitrogen ions are generated in air plasmas, two oxygen radicals are eliminated for each nitrogen ion. Because nitrogen is the main element of air, the degradation occurs quickly.
The reaction result is NO+, a stable ion that cannot react with neutral diatomic gases, but does combine with hydrocarbons to generate nitrogen oxide polymers. These polymers are resistant to additional oxidation.
The Evactron system optimizes the operating chamber pressure and plasma temperature to maximize the oxygen radical flux.
Photons in the plasma have vacuum UV (VUV) wavelengths, and VUV radiation is highly effective at breaking most organic bonds, including CH, CC, C=C, CO, and CN. Thus, pollutants with a high molecular weight are broken down into smaller, volatile components.
Numerous oxygen species produced in the plasma (O2+, O2, O3, O, O+, O, ionized ozone, metastably-excited oxygen, and free electrons) perform a second cleansing action. These species mix with organic pollutants to form H2O, CO, CO2, and low-molecular-weight hydrocarbons.
These substances have a reasonably high vapor pressure and can be easily pushed out of the microscope using the vacuum system. Figure 4 depicts the effects of plasma cleaning on a NIST SEM contamination reference sample prior to (left) and after (right) treatment.
Figure 4. The NIST contamination reference sample before (left) and after (right) plasma cleaning. Image Credit: XEI Scientific
This downstream plasma cleaning technique has proven extremely useful in electron and ion column instrumentation. It can remove unwanted hydrocarbon contamination from the inner surfaces of complex instruments without requiring disassembly.
Plasma cleaners are compact and efficient and can fit between other accessories mounted on an analytical column. Figure 5 shows an example of the Evactron® Model E16, which can be mounted flush to the microscope or with a KF40 flange. Impedance-matching electronics are set up for SEM or dual-beam FIB applications.
The compact plasma radical source is simply mounted on an analytically designed column, with most ports occupied by various spectrometers. The E-series versions were designed to run at pressures appropriate for full-speed turbopump operation.
Further research by Vane and Cable8 resulted in the creation of "Pop" ignition, which allows Evactron plasma cleaning to begin right from very high vacuum chamber pressure and then function with the turbo pump at full speed.
Figure 5. The Evactron E16 is installed on a JEOL JXA-iHP200F. The flange adapter allows the E16 to flush-mount on the top of the load lock and avoid collision with the fiber optic cable and camera on the main chamber. Image Credit: XEI Scientific
Cleaning Cycle
Cleaning is done at higher pressures than is normally present when the microscope is in operation. However, the process is quick and can often be completed shortly following a vent or sample exchange cycle.
Once the system has been cleaned, maintenance is usually as simple as a weekly cleaning that takes 10 minutes or less. This depends on the type and cleanliness of the samples introduced into the scope.
The photographs below demonstrate an improvement in the image quality of a gold-on-carbon SEM resolution sample. The image on the left was taken before cleaning with the Evactron technique, while the image on the right was obtained after plasma cleaning.
Figure 6. Images of a sputtered gold on carbon standard contaminated with hydrocarbons before (left) and after (right) Evactron plasma cleaning for 10 minutes at 20 watts power. The images were taken in a TFS/FEI Magellan 400 FEGSEM at 2 kV and 100,000X indicated magnification. Image Credit: XEI Scientific
A second benefit of this technology is that its benign nature has proven safe for common yet sensitive materials inside electron microscopes such as X-ray detector windows.
As an update to an earlier study,10 XEI Scientific and Moxtek performed a window exposure test to show that Evactron plasma cleaning will not damage the thinnest Moxtek window, the AP3.3 EDS window.11
The test subjected numerous AP3.3 windows to the oxygen radical flow from an Evactron Model E50 in an experimental vacuum chamber for almost 200 hours. After 11 years of daily cleaning, no damage was observed.
Plasma radical sources are available in various configurations to suit most electron and ion microscope manufacturers and models. Standard PRS units commonly support air or other gas combinations.
These units have KF40 flanges suitable for most SEMs and dual-beam FIB/SEMs. Because they are portable, they may be moved about to clean many electron microscopes in the laboratory.
The Evactron U50 plasma cleaner has an ultrahigh vacuum Conflat flange and is suitable for use with surface analysis equipment or other high vacuum chambers.
Downstream Plasma Cleaning in Metrology
Researchers at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, believe in eliminating all contamination from samples and chambers.
As described by Vladar et al.12 and Postek et al.3 , the work of the NIST nanoscale metrology group necessitates highly accurate SEM and helium ion microscopy at the atomic level. To obtain reproducible results, the sample must be kept as clean as possible so that it does not change significantly throughout observation.
Cleaning regimes involving a liquid nitrogen trap, clean nitrogen gas purging, cryotechniques, special pump oil, oil-free technologies, and others have all been implemented at NIST but did not meet the Institute's criteria.
However, NIST's downstream plasma cleaning approach has resulted in their adoption of the technology—employing the XEI Evactron decontamination system—because it has been identified as the only contemporary mechanism capable of meeting NIST contamination criteria.
NIST does not support a specific product or brand but strongly advocates the use of plasma-based SEM cleaning. Implementing and consistently using these approaches has enabled the elimination of electron beam-induced contamination.
The researchers at NIST created this set of photos, which show carbon contamination on a sample under a scanning electron microscope.12 The left photos show the buildup after ten minutes of scanning at 5 kV and 10 pA.
The upper image depicts the results of employing a liquid nitrogen cryo-trap. Contamination has been decreased but is still present. Compare this to the lowest pair of photos. The right-hand image displays the downstream plasma cleaning results, revealing little contamination.
Figure 7a. Contamination build up (left) Contamination reduced with use of a cold trap (right). Image Credit: XEI Scientific
Figure 7b. Contamination build up (left) Contamination reduced after plasma cleaning (right). Image Credit: XEI Scientific
Other Applications
Critical Dimension Measurements
Comparison imaging to investigate the effects of contamination on critical dimension (CD) measurements revealed that these picture artifacts can significantly change dimensional measurements.12 In CD work, the SEM imaging process modifies dimensions, resulting in a loss of measurement precision.
After 20 minutes of scanning with a very clean SEM, the test pattern in Figure 8 (left picture) began to fill in the holes. Following in-situ cleaning of the chamber and specimen, a repeat measurement revealed no hole filling and a much-reduced scan mark (right image).
Figure 8. CD test pattern showing fill-in of the holes during scanning (left) while after in situ cleaning of the chamber and specimen, a repeat of the measurement shows no filling of the holes and a much reduced scan mark. Image Credit: XEI Scientific
Artifact Removal
It is also well-acknowledged that cleaner vacuum systems can help remove spurious analytical artifacts. In many cases, carbon analysis may include contributions not from the sample but caused by contamination.
The image pair below shows the carbon contamination peaks in EDS spectra removed following plasma cleaning.
Figure 9. EDS spectra before and after plasma cleaning. Image Credit: XEI Scientific
EBSD/TKD Applications
Plasma cleaning is necessary before any EBSD investigations due to improved pattern quality and measurement efficiency.13,14 Figure 10a depicts an Evactron E50 E-TC mounted to a SEM chamber port.
For TKD studies, an electron-transparent sample is placed at a short working distance (5-7 mm) above the EBSD detector's phosphor screen (Figure 10b).
Figure 10c depicts the study's outcomes without prior plasma cleaning: after an initial period of good indexing, contamination accumulates, and pattern quality rapidly degrades, resulting in a drop in indexing. Substantial sample drift occurs, resulting in an apparent lengthening of the grain morphologies.
The study following in-chamber plasma cleaning, as shown in Fig. 10d, showed no decrease in pattern quality and consistently good indexing throughout the analysis. Minor drift was noticed, but minimum data processing could effectively characterize the microstructure.
With the most recent generation of better-sensitivity, fiber-optic-connected CMOS EBSD detectors, plasma cleaning would also allow for substantially faster and/or higher resolution analysis due to the relative improvement in diffraction pattern quality and lack of surface degradation.
Figure 10. (a) An Evactron E50 E-TC mounted on a SEM chamber port, (b) detector array around the sample, (c) deterioration of map due to contamination buildup and drift, (d) plasma cleaning prior to data collection results in good pattern quality and indexing throughout the analysis. Image Credit: XEI Scientific
Plasma cleansing the sample prior to TKD trials indicated numerous benefits. Extended investigations, which may include fast and repetitive scans at the same sample position, require improved pattern quality and measurement efficiency.
Plasma cleaning is advantageous for all high-resolution TKD and EBSD studies. It is recommended that the sample be cleaned inside the microscope chamber since it cleans the chamber, detectors, and holder all at once.
Serial Block-Face SEM
Serial Block-Face SEM (SBFSEM) is an automated method for obtaining serial pictures in an SEM for the 3D reconstruction of resin-embedded specimens. Because datasets can contain hundreds or thousands of photos, degradation of image quality due to contamination and charging can derail an investigation.
Excess contamination in backscatter detectors can reduce sensitivity to the point where the detector needs to be replaced.
Armbruster et al. found a 14% increase in BSE contrast after one set of plasma cleaning cycles, supporting the requirement for frequent cleaning as part of SBFSEM investigations.15 Figure 11 shows details of the experimental instrumentation.
Figure 11. Hardware utilized for SBFSEM experiments: a) a typical SBFSEM system, b) details of the Gatan 3View microtome, c) the Evactron EP plasma cleaner mounted on the Zeiss Sigma SEM chamber, d) a contaminated backscatter detector. Image Credit: XEI Scientific
Plasma cleaning, a normal process during SBFSEM investigations, can improve image quality, eliminate charging and contamination artifacts, accelerate pump-down, and keep the vacuum system clean during long-term data gathering.
The requirement for extended operation in scanning electron microscopes increases, as does the need to maintain pristine conditions in the vacuum chamber. SBFSEM systems must operate 24 hours a day, seven days a week, and ideally kept uncontaminated with uncompromised picture quality.
Frequently imaging big blockface resin-embedded specimens releases hydrocarbons into the vacuum chamber, decreasing detector efficiency.
For example, to ensure optimal conditions for quick imaging, Zeiss MultiSEM microscopes are outfitted with two plasma cleaners that clear adventitious hydrocarbons from the loadlock and main chamber.
Nanoscale Applications
Having clean surfaces is an absolute need for nanomanipulation and nanofabrication. The work by Mancevski has revealed that downstream plasma cleaning was crucial for successful vapor phase cutting of carbon nanotubes utilizing a nanomanipulator system.16
Electrical measurements are performed by putting minute probes on circuits utilizing nanopositioning systems placed inside SEMs and FIBs, necessitating the probes being free of contamination to create excellent contacts.
In situ cleaning of these instruments is required for precise measurements, and plasma cleaners are regarded as a must-have complement for almost all modern gadgets.
TEM Applications
Plasma cleaning is widely recognized as effective for TEM applications.17 Placing the specimen container and specimen in a plasma cleaner for a few minutes allows the user to analyze the specimen using a converged probe without polluting the viewing area.
Plasma cleaning can eliminate contamination markings from previous TEM analyses. The STEM HAADF pictures of lacy carbon support films in Figure 12 demonstrate this notion. Image A depicts a low-magnification overview of the material before cleaning.
The inset captures the same area at a greater magnification to clearly illustrate the contamination artifacts produced by the spot and scanning modes. After a 15-minute cleaning in the Evactron SoftClean™ chamber, Image B demonstrates no contamination even after one minute of stationary beam exposure.
Figure 12. STEM images before (A) and after (B) plasma cleaning of thin carbon films show the absence of contamination artifacts when plasma cleaning is used. Image Credit: XEI Scientific
Benchtop Systems
The core technology connected with downstream plasma cleaning has been enhanced to improve the system's practical usability and availability. In its early stages, plasma cleaning necessitated the use of separate systems for sample cleaning and electron microscopy.
This was because the PRS unit is normally positioned solely on electron columns and is not available for desktop use. As a result, market research revealed that many electron microscopists could not easily access a multi-purpose plasma cleaning device.
The natural approach was to merge desktop and column cleaning in a single program. XEI introduced the Evactron SoftClean™ Chamber as an example of such an instrument.
This compact, adaptable chamber can house TEM sample holders, aperture strips, tweezers, specimen clamp rings, Wehnelts, SEM samples, or small items for study under the microscope.
This chamber enables existing system users to put their Evactron plasma radical source atop the SoftClean chamber, resulting in the same downstream plasma cleaning technique and pre-cleaning without needing another direct plasma cleaning device.
This allows sensitive samples to be chemically etched securely without being subjected to high-energy ion bombardment, which could cause damage. When not used as a cleaning chamber, it can serve as a secure storage location for clean samples.
However, the user must physically connect and disconnect the instruments because the controller can only support one PRS unit at a time. The compact Evactron E16 was intended for small chamber cleaning and is the SoftClean system's recommended model.18
Figure 13. (Left photo) A complete Evactron E16/SoftClean system includes the SoftClean vacuum chamber with specimen rack and the Evactron E16 plasma cleaner, including the plasma radical source, controller, E-TC touchpad, and cables. The modular system easily fits into small benchtop spaces. (Right photo) The Evactron E16 plasma cleaner can be attached to a SEM by means of a flush-mount system as shown or by means of a KF40 adapter. Image Credit: XEI Scientific
Conclusions
Downstream plasma cleaning has become a highly successful method for extracting the most accurate pictures and analytical data from advanced electron and ion column equipment. Evactron plasma cleaners are effective tools for removing hydrocarbon contamination from samples, holders, and microscopes themselves.
This downstream plasma cleaning method enables researchers in various domains to improve their microscopes' performance while investigating, imaging, analyzing, and manipulating materials. XEI Scientific has approximately 5000 tools installed on almost every SEM and dual beam FIB/SEM make and model.
Most high-resolution tools now include some downstream plasma cleaning when delivered from the factory. To optimize SEM performance, service workers frequently bring an Evactron with them on field service and preventative maintenance trips.
References
- Vane, R. and Moore, C.A. (2014). Advancements in Decontamination of Vacuum Systems Using Plasma Cleaning. Microscopy and Microanalysis, 20(S3), pp.1130–1131. https://doi.org/10.1017/s1431927614007387.
- Kosmowska, E., et al. (2017). Improved Pump Down Time with Evactron® Turbo Plasma™ Cleaning. Microscopy and Microanalysis, (online) 23(S1), pp.74–75. https://doi.org/10.1017/s1431927617001052.
- Postek, M.T., Vladár, A.E. and Purushotham, K.P. (2013). Does your SEM really tell the truth? How would you know? Part 2. Scanning, 36(3), pp.347–355. https://doi.org/10.1002/sca.21124.
- Sullivan, N., et al. (2002). A Study of the Effectiveness of the Removal of Hydrocarbon Contamination by Oxidative Cleaning Inside the Sem. Microscopy and Microanalysis, 8(S02), pp.720–721. https://doi.org/10.1017/s1431927602106234.
- Vane, R., et al. (2019). 20th Anniversary of Evactron® Plasma Cleaners for SEMs and FIBs. Microscopy and Microanalysis, 25(S2), pp.550–551. https://doi.org/10.1017/s1431927619003489.
- Vane, R. and Kosmowska, E. (2016). Remote Plasma Cleaning and Radical Recombination Rates. Microscopy and Microanalysis, 22(S3), pp.46–47. https://doi.org/10.1017/s1431927616001082.
- Armbruster, B.L. (2023) M&M 2023 Meeting (Microscopy & Microanalysis). Available at: https://mm2023.eventscribe.net/fsPopup.asp?efp=WVJYU1dYTkcyMDAxNg&PresentationID=1263244&rnd=5.559349E-02&mode=presInfo.
- Vane, R. and Cable, M. (2015). Effective New Plasma Cleaning Strategies for Scanning Electron Microscopes and FIBs. Microscopy and Microanalysis, 21(S3), pp.161–162. https://doi.org/10.1017/s1431927615001609.
- Vane, R. and Cable, M. (2018). Using a Residual Gas Analyzer to Monitor Plasma Cleaning of SEM Chambers and Specimens. Microscopy and Microanalysis, 24(S1), pp.1152–1153. https://doi.org/10.1017/s1431927618006244.
- Vane, R., Roberts, C. and Carlino, V. (2004). A Study of the Effects of Evactron® Plasma Cleaning on X-ray Windows. Microscopy and Microanalysis, 10(S02), pp.966–967. https://doi.org/10.1017/s1431927604883818.
- Kosmowska, E., et al. (2018). The Effects of Evactron® Plasma Cleaning on Moxtek® X-ray Windows. Microscopy and Microanalysis, (online) 24(S1), pp.682–683. https://doi.org/10.1017/s1431927618003902.
- Andras Vladar, Postek, M.T. and Vane, R. (2001). Active Monitoring and Control of Electron-Beam-Induced Contamination. NIST, (online) 4344, pp.835–843. Available at: https://www.nist.gov/publications/active-monitoring-and-control-electron-beam-induced-contamination (Accessed 21 Feb. 2025).
- Fanta, A.B., et al. (2018). Elevated temperature transmission Kikuchi diffraction in the SEM. Materials Characterization, (online) 139, pp.452–462. https://doi.org/10.1016/j.matchar.2018.03.026.
- Armbruster, B., et al. (2020). The Benefits of Plasma Cleaning for TKD/EBSD Analysis. Microscopy and Microanalysis, (online) 26(S2), pp.2702–2703. https://doi.org/10.1017/s1431927620022485.
- Armbruster, B., et al. (2017). Plasma Cleaning Improves the Image Quality of Serial Block-face Scanning Electron Microscopy (SBFSEM) Volumetric Data Sets. Microscopy and Microanalysis, 23(S1), pp.1266–1267. https://doi.org/10.1017/s1431927617006997.
- Mancevski, V. (2011). Fabrication and analysis of carbon nanotube based emitters. (online) Handle.net. Available at: http://hdl.handle.net/2152/ETD-UT-2011-08-3990 (Accessed 21 Feb. 2025).
- Morgan, C., Varley, D. and Vane, R. (2010). Remote Plasma Cleaning from a TEM Sample Holder with an Evactron® De-Contaminator. Microscopy and Microanalysis, 16(S2), pp.48–49. https://doi.org/10.1017/s1431927610055303.
- Vane, R., et al. (2021). Two New Evactron® Plasma Cleaners for Small Chambers and UHV Systems. Microscopy and Microanalysis, 27(S1), pp.1644–1646. https://doi.org/10.1017/s1431927621006061.
- Armbruster, B., et al. Evactron®. (2020). Visualizing Evactron® Turbo Plasma™ Cleaning in nanoflight® Movies - Evactron®. (online) Available at: https://evactron.com/pdf/visualizing-evactron-turbo-plasmatm-cleaning-in-nanoflight-movies/ (Accessed 21 Feb. 2025).
- Gleason, M., Morgan, C. and Vane, R. (2007). Using a Thickness Monitor to Measure Contaminant Removal by Evactron Cleaning as a Function of Operating Parameters. Microscopy and Microanalysis, (online) 13(S02). https://doi.org/10.1017/s1431927607074132.
- Vane, R. US Patents 6,105,589 (issued Aug. 2000) and 6,452,315 (issued Sept. 2002).
This information has been sourced, reviewed and adapted from materials provided by XEI Scientific.
For more information on this source, please visit XEI Scientific.