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10 Deposition As FIB technology is frequently used for milling an additional technique can convert the ion beam system into a deposition system allowing the addition of material instead of removing material. This is realized by adding a so-called gas delivery system, that locally supplies a chemical compound close to the surface impact point. The chemical gas compound often consists of a organic-metallic molecule such as methyl cyclo pentadienyl Pt (IV) tri methyl. When this compound is exposed to the ion beam it will decompose locally and deposit Pt onto the surface. In general the cracking of the molecule is not 100% so there are always some additional matrix molecules such as organic residues that are also deposited. The purity of the deposit is therefore generally lower compared to, for example, CVD deposits. The main advantage in comparison to CVD or PVD is the highly local deposition, and the capability to create different heights of the deposit in one exposure. In addition the direct deposition capability is flexible and does not require complex mask structures. Molecules are absorbed on the irradiated area, and by using the patterning capability of the system three dimensional structures can be grown at selected positions, with full control of size, position and height. So this capability is a very welcome addendum to the FIB’s milling power. The material deposited depends on the gas chemistry used and various options are possible. Readily available gas chemistry allows the deposition of Pt, W, SiO2, C. Figure 17: Light microscope image of the sample deposited ex-situ on a TEM grid. Ex-situ foil extraction using electro-static probes works even for materials with low structural integrity. Important characteristics for the depositions are the minimum size (typically around 50 nm), the purity of the material, and its conductivity which is usually lower than the pure metal. Creation of TEM lamella An important capability, derived from the system’s milling capacity, is the creation of thin lamella that are transparent to an electron beam and hence can serve as a TEM sample. As the position of the ion beam can be controlled to a high degree, the TEM lamella can be created at any location that is of interest to the user. Focused ion beam machining for the creation of TEM samples is now firmly established as the most versatile and accurate method currently available. There are several ways to extract the FIB machined foil from the bulk sample without having to use mechanical preparation at all, so for the first time it is not necessary to sacrifice the sample when performing TEM analysis with the highest accuracy. Site specific The fact that the location of the foil site can be defined inside the FIB makes this the only true site-specific technique available. The momentary feed-back of what and where FIB milling takes place is essential to generate the best samples from the region of interest. Lateral placement of foils is quite simple, and the aimed thickness is in the range of 100 nm and can be controlled to a high degree. Material independent As the ion beam removes atoms from the sample in an atomic collision process rather than with a mechanical bulk cut or mechanical polish, the amount of ions needed to remove different materials with varying hardness is not related to the structure or the composition of the sample. This means that milling any material or a combination of materials is as straightforward as a simple single crystal sample for ion beam machining. Even voided, brittle or soft/hard combinations of materials are easy for the FIB process. Many TEM samples that were difficult or impossible to make until now (soft polymer coating on metal, hard metal on soft metal) are now easy to make using FIB technology.
Automated and executed unattended FEI is the only company to offer a fully functional and integrated automatic TEM sample preparation capability. By combining image recognition software with the full software control of patterning, stage and beam position the process can be run automatically, even without operator presence. Multi-sites possible This function can be extended to run overnight and dozens of foils can be prepared automatically, providing a significant enhancement to instrument effectiveness not only for the FIB instrument but also for the TEM used in the subsequent analysis. Figure 18: Automated TEM sample preparation is now being used on a wide variety of materials with the highest success rate. This image shows a multi-site TEM sample preparation in olive rock, allowing many samples from positions to be well-defined and close to each other. No other technique allows this high flexibility. Figure 19: TEM image of a FIB prepared foil showing a 12° Mg-silicate grain boundary in a synthetic bi-crystal. High quality foils from a wide variety of materials are straightforward and permit the most demanding TEM applications with all the benefits of FIB preparation. Mill Allignment Marks Figure 20: The 6 stages of automated TEM sample preparation. Micro and nano patterning Thin to < 1 µm Deposit Protective Layer Cut out Membrane Bulk Milling Final Thinning < 50 nm Control the specialized micro-structure fabrication with FIB as it delivers rapid three dimensional process control and hence reduces the product development cycle. As FIB has accurate control over milling parameters as well as over deposition parameters, it is the ideal tool to quickly create small structures in the top-down approach for nano-technology. It is a mask-less technique and highly flexible and fast for a serial technique. These qualities make FIB valuable for prototyping and design modifications. MEMS and NEMS prototyping If a prototype device does not fulfill its specification and is unable to deliver the right result, it can be directly modified with FIB until it does. The process technology required to create 3D micro-structures is expensive, complex and can take months to perfect. By using the direct modification capabilities of ion beam machining combined with instant deposition and etching chemistries, real results can be achieved while the 11
Page 1: Focused ion beam technology, capabi
Page 4 and 5: Technology 4 Electrons replaced by
Page 6 and 7: 6 Useful signals As many signals ar
Page 8 and 9: 8 Anode Lens 1 Scan & Stig Coils El
Page 12 and 13: 12 Figure 21: Cantilever with proof
Page 14 and 15: Application examples 14 The New Dim
Page 16 and 17: 16 Figure 42: FIB machined photonic
Page 18 and 19: 18 Figure 49: SE image made with io
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Focused ion beam technology, capabilities and ... - FEI Company

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