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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Focused ion beam | 3/3 | https://en.wikipedia.org/wiki/Focused_ion_beam | reference | science, encyclopedia | 2026-05-05T10:04:34.384165+00:00 | kb-cron |
=== FIB-SEM tomography === The focused ion beam has become a powerful tool for site-specific 3D imaging of sub-micron features in a sample. In this FIB tomography technique, the sample is sequentially milled using an ion beam perpendicular to the specimen while imaging the newly exposed surface using an electron beam. This so-called "slice and view" approach allows larger scale nano-structures to be characterized across the many imaging modes available to an SEM, including secondary electron, backscattered electron, and energy dispersive x-ray measurement. The process is destructive, since the specimen is being sequentially milled away after each image is collected. The collected series of images is then reconstructed to a 3D volume by registering the image stack and removing artifacts. The predominant artifact that degrades FIB-SEM is ion mill curtaining, where mill patterns form large aperiodic stripes in each image. The ion mill curtaining can be removed using destriping algorithms. FIB-SEM can be done at both room and cryo temperatures as well as on both materials and biological samples. It is one of several approaches in Volumetric Electron Microscopy.
== History == History of FIB technology
1975: The first FIB systems based on field emission technology were developed by Levi-Setti and by Orloff and Swanson and used gas field ionization sources (GFISs). 1978: The first FIB based on an LMIS was built by Seliger et al. Physics of LMIS
1600: Gilbert documented that fluid under high tension forms a cone. 1914: Zeleny observed and filmed cones and jets 1959: Feynman suggested the use of ion beams. 1964: Taylor produced exactly conical solution to equations of electro hydrodynamics (EHD) 1975: Krohn and Ringo produced first high brightness ion source: LMIS Some pioneers of LMIS and FIB
Mahoney (1969) Sudraud et al. Paris XI Orsay (1974) Hughes Research Labs, Seliger (1978) Hughes Research Labs, Kubena (1978–1993) University of Oxford Mair (1980) Culham UK, Roy Clampitt Prewett (1980) Oregon Graduate Center, L. Swanson (1980) Oregon Graduate Center, J. Orloff (1974) MIT, J. Melngailis (1980)
== Helium ion microscope (HeIM) ==
Another ion source seen in commercially available instruments is a helium ion source, which is inherently less damaging to the sample than Ga ions although it will still sputter small amounts of material especially at high magnifications and long scan times. As helium ions can be focused into a small probe size and provide a much smaller sample interaction than high energy (>1 kV) electrons in the SEM, the He ion microscope can generate equal or higher resolution images with good material contrast and a higher depth of focus. Commercial instruments are capable of sub 1 nm resolution.
== Wien filter in focused ion beam setup ==
Imaging and milling with Ga ions always result in Ga incorporation near the sample surface. As the sample surface is sputtered away at a rate proportional to the sputtering yield and the ion flux (ions per area per time), the Ga is implanted further into the sample, and a steady-state profile of Ga is reached. This implantation is often a problem in the range of the semiconductor where silicon can be amorphised by the gallium. In order to get an alternative solution to Ga LMI sources, mass-filtered columns have been developed, based on a Wien filter technology. Such sources include Au-Si, Au-Ge and Au-Si-Ge sources providing Si, Cr, Fe, Co, Ni, Ge, In, Sn, Au, Pb and other elements. The principle of a Wien filter is based on the equilibrium of the opposite forces induced by perpendicular electrostatic and a magnetic fields acting on accelerated particles. The proper mass trajectory remains straight and passes through the mass selection aperture while the other masses are stopped. Besides allowing the use of sources others than gallium, these columns can switch from different species simply by adjusting the properties of the Wien filter. Larger ions can be used to make rapid milling before refining the contours with smaller ones. Users also benefit from the possibility to dope their samples with elements of suitable alloy sources. The latter property has found great interests in the investigation of magnetic materials and devices. Khizroev and Litvinov have shown, with the help of magnetic force microscopy (MFM), that there is a critical dose of ions that a magnetic material can be exposed to without experiencing a change in the magnetic properties. Exploiting FIB from such an unconventional perspective is especially favourable today when the future of so many novel technologies depends on the ability to rapidly fabricate prototype nanoscale magnetic devices.
== See also == Confocal microscopy Ion milling machine Powder diffraction Ultrafast x-ray X-ray crystallography X-ray scattering techniques
== References ==
Hoffman, David P.; Shtengel, Gleb; Xu, C. Shan; Campbell, Kirby R.; Freeman, Melanie; Wang, Lei; Milkie, Daniel E.; Pasolli, H. Amalia; Iyer, Nirmala; Bogovic, John A.; Stabley, Daniel R.; Shirinifard, Abbas; Pang, Song; Peale, David; Schaefer, Kathy; Pomp, Wim; Chang, Chi-Lun; Lippincott-Schwartz, Jennifer; Kirchhausen, Tom; Solecki, David J.; Betzig, Eric; Hess, Harald F. (2020). "Correlative three-dimensional super-resolution and block-face electron microscopy of whole vitreously frozen cells". Science. 367 (6475) eaaz5357. doi:10.1126/science.aaz5357. ISSN 0036-8075. PMC 7339343. PMID 31949053.
== Further reading == Mackenzie, R A D (1990). "Focused ion beam technology: a bibliography". Nanotechnology. 1 (2): 163–201. Bibcode:1990Nanot...1..163M. doi:10.1088/0957-4484/1/2/007. S2CID 250854112. J. Orloff (2009). Handbook of Charged Particle Optics. CRC Press. ISBN 978-1-4200-4554-3. L.A. Giannuzzi; F.A. Stevie (2004). Introduction to Focused Ion Beams: Instrumentation, Theory, Techniques and Practice. Springer Press. ISBN 978-0-387-23116-7.