Focused ion beam technology, capabilities and ... - FEI Company

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8 Anode Lens 1 Scan & Stig Coils Electron Beam Electron Beam impact area Turbo/ diff pump E-Beam Ion-Beam E source Gun align coils Lens 2 Lens 3 Final lens body Collector system Secondary electrons Roughing line (to rotary etc...) Figure 9: Graph indicating the usefulness of the many apertures in the ion column, so that for various ion beam settings the system can always be optimized by selecting the proper aperture. Figure 10: SE image induced by ion beam of isolated bond pad on an IC device. Structures are masked by strong contrast and chargelines. Extractor Lens 1 Blanking plates Lens 2 Octopole for stigs, scan etc... Impact area of Ion Beam Sample Turbo pump Ga + LMI source Suppresser Octopole alignment Blanking aperture Continuous dinode detector Electrons or ions imaging Roughing line (to rotary etc...) Figure 8: Schematic presentation of SEM and FIB and the many similarities of the instruments. Figure 11: Ion image of the same structure. This also shows strong charging of the sample prohibiting a good view of the sample. Figure: 12 Ion image but now recorded with flood gun on. The spray of electrons has eliminated the charge build-up and details become apparent.
Capabilities of the focused ion beam system Apart from the superb FIB imaging capabilities obtained by regular scanning of the (low current) ion beam, the system can also translate a pattern of doses onto the sample and induce active and controlled surface milling. Milling As is shown by the basic interaction of the ion beam with the sample, milling is a continuous process that always occurs during beam exposure. The milling process as such is an atomic collision process. The milling rate (µm3 /s) is (linear) proportional to the beam current and high amounts of material are removed with high beam currents. In addition, precise control is possible by the use of smaller spot sizes and hence smaller currents. A typical rectangular area of 10 x 5 x 3 µm can take around 10 minutes for complete removal. As the ion beam position is well controlled, milling can be used to create a simple structure such as a square or round hole in the material, but also a more complex pattern as shown below. 3.1 µm Figure 13: Image of a direct write ion beam nano-pattern in gold. Time to result is 8 minutes. Milling of complex patterns and arbitrary shapes defined in bitmaps are a basic function of the system. Milling is the most powerful capability of the focused ion beam and directly related to the choice of ion, its energy range and the momentum of the particle (its weight). Milling allows the freedom to manipulate the sample, open it up in the third dimension and create a cross-section, or to create any possible shape as “carved in stone”. Not only the lateral position, but also the local depth can be controlled. In this way milling is different from etching with a mask on the sample. Removal of atoms from the surface can be enhanced by the addition of local chemistry in the form of a gas delivery system. This local supply of gas can, for example, change the oxidation of released particles and may Figure 14: Example of a cross-section imaged and made by the FIB. The cross-section shows an insulation defect on a semi-conductor device. substantially speed up the milling process. In general it will also reduce the local re-deposition of atoms released from the surface. Examples of gases that are used to enhance milling are I2 and XeF2. Figure 15: Silicon surface showing both milling and deposition capabilities as examples of the creation of local structures. A, B, C and D are micro-depositions, whereas E, F and G are structures milled into the sample. Figure 16: In-situ foil extraction using micromanipulators in the chamber. The next stage is that the TEM lamella shown on the tip is deposited on a TEM grid, or “micro-welded” onto a support ring that fits in the TEM. 9
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 10 and 11: 10 Deposition As FIB technology is
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
Page 20: FEI Company World Headquarters and

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