By Shiladitya Chatterjee and Matthew R. Linford, Department of Chemistry and Biochemistry, Brigham Young University, Utah, USA Contributing Editors Highlights from the 2016 Microscopy & Microanalysis Meeting in Columbus, OH. A New MS/MS Imaging ToF-SIMS Mass Spectrometer, a Very Low Cost AFM, and a Remote Plasma Cleaning System

e recently attended the 2016 (SE): Uniqueness Plots and Width Func- do not wish any vendors to feel like the Microscopy & Microanalysis tions in XPS, and Distance, Principal lack of an invitation to contribute to this W(M&M) meeting held at the Component, and Cluster Analyses in SE”. article is in any way a judgment of their Columbus Convention Center in Colum- These are topics we have recently pub- product. We are not trying to endorse bus, Ohio. Columbus is a beautiful, clean lished on in the Linford group.1-4 any products here. Finally, in the spirit of city. We arrived the Saturday before the Many of the sessions encouraged stu- our earlier articles, we hope to provide a conference and that evening attended a dent participation and there were a num- technical/tutorial view and commentary minor league baseball game (Columbus ber of student awards. In our experience, of the science and technology behind the Clippers). The home team won. Both pic- M&M 2016 drew an exceptional group of products we will be discussing. tures above are from the trip, and the pic- scientists and engineers. The next M&M ture of MRL was taken at the game. annual meeting will be in St. Louis, MO. v The M&M conference is an excellent We hope to see you there. meeting for anyone working in the fields In general when we go to conferences of microscopy, microanalysis, and thin we spend some time in the exhibition TOF-SIMS Parallel Imaging MS/MS film characterization. The conference ran hall. This is a great way to find out about Company:  from July 24 – 28, 2016 and each day what’s new. Indeed, because our ability to featured 3 parallel sessions with topics synthesize and characterize many of the Physical Electronics such as advances in instrumentation and materials we work with depends on the (a division of ULVAC-PHI) microscopy in the biological and physical process and analytical tools at our disposal, Company Website: sciences. There were great posters in the thin film and material characterization are www.phi.com/physical-electronics.html evenings on a myriad of topics, including never far from advanced instrumentation. Company Contact: microfabrication, image processing, and Accordingly, we extended an invitation [email protected] nanomaterials. SC gave a poster entitled: to a few of the vendors at M&M 2016 to “Polyallylamine as an Adhesion Promoter provide us with information we might use Company Overview: for SU-8 Photoresist”. MRL gave an in- in a VT&C article. Three of them sent us According to the company, “Physical vited talk on “New Data Analysis Tools the content that we based this article on. Electronics (PHI) is a subsidiary of UL- for X-Ray Photoelectron Spectroscopy Of course we were not able to visit most VAC-PHI, the world’s leading supplier (XPS) and Spectroscopic Ellipsometry of the booths at the conference, and we of UHV surface analysis instrumentation

2 [email protected] September 2016 • Vacuum Technology & Coating used for research and development of becomes enormous. Today, analyses rou- by a 1 Da precursor selection window, is advanced materials in a number of high tinely produce secondary ion masses well accomplished by a 1.5 keV Collision-In- technology fields including: nanotech- over 2,000 m/z. Clearly, to further extend duced-Dissociation (CID) cell using Ar nology, microelectronics, storage media, the technique an advance is needed in the gas. Lateral resolutions produced in both bio-medical, and basic materials such as data acquisition of higher mass molecular MS1 and MS2 images were shown in the metals, polymers, and coatings. PHI’s ion fragments in order for TOF-SIMS to presented research to be < 200 nm. The innovative XPS, AES, and SIMS technol- reach its full potential for unambiguous MS2 fragment spectra from a sample of ogies provide our customers with unique compound identification and ease of data pure Crystal Violet demonstrates that the tools to solve challenging materials prob- interpretation. This is particularly import- 1 Dalton wide precursor selection win- lems and accelerate the development of ant for cellular and sub-cellular biological dow can eliminate or select 13C-contain- new materials and products.” tissue analysis, as well as micro-features ing precursor peaks, providing enhanced Product Description: on polymers, biomaterials and other or- MS2 data from samples with complex At the time of its introduction in the ganic materials. mixtures of additives on the surface. This 1980’s, Time-of-Flight Secondary Ion To provide this needed paradigm shift, data bodes well for imaging of lipids and Mass Spectrometry (TOF-SIMS) was Physical Electronics has designed a rev- metabolites from tissue samples. The principally a surface analysis research olutionary new TOF-SIMS Parallel Im- MS2 fragment ion spectra also demon- instrument. It provided elemental ion and aging MS/MS. Results from this unique strate better than 10 ppm mass accuracy 5 limited molecular fragment ion spectra and patented instrument were presented for the identified peaks. The conversion and images of the outer layers of solid ma- at the Microscopy and Microanalysis efficiency of precursor ion peaks to the terials. TOF-SIMS is based on the impact Conference in Columbus, Ohio – John spectrum of fragment ion peaks is, on av- of a finely focused, raster-scanned ion Hammond gave a talk on it. The newly erage, better than 10%. beam on the surface of the sample and the developed TOF-TOF tandem imaging A schematic of the PHI nanoTOF II time-of-flight mass analysis of the ejected mass spectrometer system allows con- imaging MS/MS is shown in Figure 1. The secondary ions (SIMS). Since its initial ventional TOF-SIMS (MS1) analysis and system design allows simultaneous MS successes, TOF-SIMS has evolved into a product ion (MS/MS or MS2) analysis to and MS/MS imaging up to 8 kHz, allowing more powerful technique for spectroscopy be acquired simultaneously and in par- MS1 and MS2 imaging and spectroscopy and imaging of molecular fragment ions. allel. Secondary ions for MS1 and MS2 in less than 15 minutes. Figure 2 shows This has been achieved, in part, by two or- analysis are produced from the same area a negative polarity MS2 spectrum of the ders of magnitude improvement in higher of the surface by a pulsed and digitally Erucamide polymer additive precursor mass ionization efficiencies. Improved raster-scanned primary ion nanoprobe. molecular ion. This spectrum allows the spatial focusing of the primary ion beams Activation of the precursor ions, defined structural identification of the location of has also improved the ultimate spatial res- olution observed for TOF-SIMS imaging of molecular fragment ions. All of these advances have expanded the breadth of applications, most nota- bly the use of TOF-SIMS for analyzing organic contamination, tissue cross sec- tions, pharmaceuticals, and polymer sur- faces with sub-micron spatial resolution. Nevertheless, the limitation of organic molecular fragment compositional peak assignments, based on TOF mass reso- lutions of up to 16,000 m/Δm and mass accuracies of ca. 10 to 20 ppm for current state-of-the-art TOF analyzers, has creat- ed ambiguity for many of the peak assign- ments above 200 m/z (for either positive or negative polarity ions). That is, there is uncertainty in peak assignments because the TOF mass spectrometers have tra- ditionally had good, but not great, mass resolution, and as the molecular weight of a fragment increases the number of pos- sible ways the elements can be combined Figure 1. Schematic of the Phi TOF-SIMS Imaging MS/MS instrument. Figure obtained and to make a fragment of the same mass used with permission from Phi (www.phi.com).

Vacuum Technology & Coating • September 2016 www.vtcmag.com 3 Figure 2. MS/MS spectrum of the m/z 336 erucamide precursor ion. Figure obtained and used with permission from Phi (www.phi.com). the double bond. Figure 3 shows the MS1 images for a heat-treated polyethylene terephthalate film and the MS2 images from the positive polarity 577 m/z precursor ions. The simultaneous MS1 and MS2 imaging of the heat-treated PET sample confirmed that the crystal structure on the surface of the PET has a cyclic trimer structure. The MS1 images and MS2 images derived from the CID activation of the positive polarity 577 m/z precursor show that the crystal images are in exact registry with one another. Line scans (80% to 20% intensity) show <200 nm spatial resolution for both modes of imaging. Figure 4a shows the MS1 Figure 3. MS1 images and MS/MS (MS2) images from positive polarity m/z 577 precursor image for the granulomas in the cross- ions from a heat treated PET film. Figure obtained and used with permission from Phi section of the spleen of Zebrafish infected (www.phi.com). with Mycobacterium Marinum (a form of marine tuberculosis). Figure 4b and 4c show the elevated MS2 intensities of fatty acids (FA 16:0) around the granulomas, thought to be the result of metabolism of lipids in the macrophages trying to attack the infection in the granulomas. The spatial resolution of the elevated fatty acids observed in the MS2 image is 0.8 microns in Figure 4d.6 These results confirm that TOF-SIMS Imaging MS/MS can now provide easy and unambiguous molecular fragment ion peak identification and fast parallel imaging with MS1 and MS2 data. Further information can be obtained at www.phi.com. v

Figure 4. (a) MS1 image of granulomas from the cross-section of an infected spleen of a Ze- brafish, (b) and (c) the MS2 images of the fatty acid (16:0) distribution, (d) 0.8 micron spatial resolution of the elevated fatty acid intensities. Figure obtained and used with permission from Phi (www.phi.com).

4 [email protected] September 2016 • Vacuum Technology & Coating Figure 5. The nGauge AFM system (left) is a compact instrument that includes a coarse approach mechanism, an AFM chip, and integrated electronics. The CMOS-MEMS chip (right) is bonded to a printed circuit board that is easy to handle. Figure obtained and used with permission from ICSPI Corp. Low cost Atomic Force Microscope one would need another microscope just anism, this chip is the entire AFM. Ex- (AFM), the nGauge AFM to see it. Through miniaturization and in- tremely precise MEMS actuators provide tegration they are making this powerful sub-nanometer positioning while inte- Company: instrument more accessible to those who grated piezo resistive sensors provide pre- ICSPI Corp. can benefit most from it, while enabling cision low-noise measurements. Unlike a Company Contact: new applications for experienced users. conventional AFM which has large exter- [email protected] This technology is being commercialized nal scanners, a complex laser alignment as a small, simple, affordable desktop tool system, miniscule probes to exchange, Company Overview: called the nGauge AFM.” and a large vibration isolation system, the According to the company, “Integrated entire nGauge AFM uses a single-chip Product Description: Circuit Scanning Probe Instruments (ICS- AFM and some small, low-cost hardware According to the company, the nGauge PI, pronounced “icy spy”) is a Microsys- to achieve results comparable to machines AFM is the smallest, simplest, and most tems company that was spun off from the that cost 100x more. The software, me- affordable AFM on the market. The University of Waterloo to produce the first chanical drawings, and electrical design X/Y/Z scanners, the sensors, and the single-chip Atomic Force Microscope will be open-sourced. (AFM). After nearly 10 years of research sharp tip of an AFM have all been in- into CMOS-MEMS technology, the com- tegrated into a single 1 × 1 mm MEMS pany has developed an AFM so small that chip. Apart from a coarse approach mech- v Remote Plasma Cleaning System plasma cleaners have been sold and XEI The technical program of the M&M is now shipping its 4th generation of conference showed how Evactron® plas- Company: Evactron products.” As an aside, we have ma cleaning has become an indispensable XEI Scientific, Inc. an Evactron plasma system on our XPS tool for advanced SEM technologies.7 For Company Website: at BYU. example, low-energy energy dispersive www.evactron.com Product Description: X-ray spectroscopy (EDS) is now practi- The Evactron® EP model was demon- cal because there is no carbon absorption Company Contact: 8 strated at the Microscopy and Microanal- of soft x-rays in clean chambers. Accu- [email protected] ysis Conference. It features high vacuum rate electron energy loss (EELS) mea- Company Overview: start and operation, the highest Evactron surements also require a carbon-free envi- According to the company “XEI invented hydrocarbon removal rates, dual mode ronment. Electron backscatter diffraction and introduced the Evactron® Decomtam- UV plus oxygen radical cleaning, and a (EBSD) sensitivity degrades if low en- inator in 1999. It is the industry standard small plasma source. The plasma source ergy backscatter signals are absorbed by for remote plasma cleaning of scanning has a simple on/off start and blutooth carbon. Long scans must not redeposit electron microscopes (SEMs), focus ion Android tablet control to call up pre-pro- carbon on nanoprobes from contaminated beams (FIBs), and vacuum chambers to grammed recipes. Cleaning times are typ- chamber or sample surfaces. Backscat- remove hydrocarbons from chamber and ically 1 – 5 minutes, and clean columns ter electron detectors can be cleaned by specimen surfaces. Over 2400 Evactron exhibit speedy pump down times. plasma instead of being replaced, saving

Vacuum Technology & Coating • September 2016 www.vtcmag.com 5 Figure 6. Picture of the Evactron® EP with controller. Figure obtained and used with permission from XEI Scientific. time and money. Hydrocarbons must be Uniqueness plots: A simple graphical tool prevented from condensing on specimens for identifying poor peak fits in X-ray pho- and interfering with imaging during cryo- toelectron spectroscopy. Applied Surface SEM experiments. These examples and Science 2016, 387, 155-162. others have become practical on stan- 2. Singh, B.; Velázquez, D.; Terry, J.; Linford, M. R., Comparison of the equivalent width, dard commercial SEMs with the easy the autocorrelation width, and the variance availability of Evactron plasma cleaning. as figures of merit for XPS narrow scans. Papers mentioning plasma cleaning as a Journal of Electron Spectroscopy and Re- prerequisite were found in many sessions lated Phenomena 2014, 197, 112-117. at the conference. 3. Singh, B.; Velázquez, D.; Terry, J.; Linford, The Evactron EP and ES models and M. R., The equivalent width as a figure of the more flexible Zephyr model have merit for XPS narrow scans. Journal of enabled TurboPlasma™ cleaning at the 1 Electron Spectroscopy and Related Phe- to 40 millitorr range when using a turbo nomena 2014, 197, 56-63. molecular pump (TMP) pumping system. 4. Bagley, J. D.; Dennis Tolley, H.; Linford, TurboPlasma cleaning brings the “Fast- M. R., Reevaluating the conventional approach for analyzing spectroscopic el- est way to Pristine” using both UV light lipsometry psi/delta versus time data. Ad- from a flowing afterglow plus the oxygen ditional statistical rigor may often be appro- chemical etch of remote plasma cleaning. priate. Surface and Interface Analysis 2016, Tests with a RGA (residual gas analyzer 48 (4), 186-195. mass spectrometer) show that heavy con- 5. Larson, P. E.; Hammond, J. S.; Fisher, G. tamination with hydrocarbons can be re- L.; Heeren, R. M., Method and apparatus to moved in less than 10 minutes to less than provide parallel acquisition of mass spec- 10-9 Torr. The Evactron EP is a compact trometry/mass spectrometry data. Google and simplified model that is easy to op- Patents: 2015. erate and less expensive, but retains high 6. Fisher, G. L.; Bruinen, A. L.; Ogrinc Po- performance cleaning. točnik, N.; Hammond, J. S.; Bryan, S. R.; Larson, P. E.; Heeren, R. M., A New Method and Mass Spectrometer Design for v TOF-SIMS Parallel Imaging MS/MS. Anal Acknowledgments Chem 2016. 7. Vane, R.; Kosmowska, E., Remote Plas- PHI, ICSPI, and XEI have granted to ma Cleaning and Radical Recombination VT&C the right to publish both the text Rates. Microscopy and Microanalysis and the images provided to VT&C that 2016, 22 (S3), 46-47. are published herein. 8. Burgess, S.; Holland, J.; Statham, P.; Mc- Carthy, C., Windowless EDS Detection of N Lines and their Practical use in sub 2 kV References X-ray mapping to Optimize Spatial Resolu- 1. Singh, B.; Diwan, A.; Jain, V.; Herre- tion. Microsc. Microanal 2016, 22, 3. ra-Gomez, A.; Terry, J.; Linford, M. R.,

6 [email protected] September 2016 • Vacuum Technology & Coating