Convenient Preparation of High-Quality Specimens for Annealing Experiments in the Transmission Electron Microscope

ABSTRACT: A procedure based on focused ion beam milling and in situ lift-out is introduced for the preparation of high-quality specimens for in situ annealing experiments in the transmission electron microscope. The procedure allows an electron-transparent lamella to be cleaned directly on a heating chip using a low ion energy and back-side milling in order to minimize redeposition and damage. The approach is illustrated through the preparation of an Al–Mn–Fe complex metallic alloy specimen.

Figure left: Schematic diagram showing the configuration of an FEI dual-beam FIB Helios workstation with the α-flip (AF) holder mounted on the stage. The solid orange lines show the AF and tiltangles. The dotted orange line shows the total tilt angle of thespecimen compared with the horizontal. The inset shows a schematic diagram of a transmission electron microscopic lamella to define the terms used in the text. FIB, focused ion beam.

Figure above: a-c: Focused ion beam (FIB) and (d–f) scanning electron microscopic (SEM) images of the different thinning steps. The tilt angles and milling parameters are given in Table 1: (a) and (d) were acquired after transfer of the lamella onto the chip; (b) and (e) were acquired after milling at 81 pA (step 17 in Table 1); and (c) and (f) after milling at 47 pA (step 18 in Table 1); (g) bright-field; (h) dark-field; and (i) high-angle annular dark-field scanning transmission electron microscopic (STEM) images taken with the STEM detector of the FEI dual-beam Nanolab FIB Helios system. The scale bar for the FIB and SEM images is given in (f), while the scale bar of the STEM images is given in (i). The dot line in (a) shows the edge of the V shape created by the milling in steps 4 and 5 in Table 1, in this way the middle of the lamella can be found when using the back-side milling configuration during the thinning procedure.

Figure left: High-resolution transmission electron microscopic images of the complex metallic alloy specimen attached to a DENSsolutions double-tilt heater chip for annealing experiments. a: Lower side of the lamella in the back-side milling configuration [exposed to the focused ion beam (FIB) during the thinning procedure]. b: Magnified area shown by the red box in (a), ∼50 nm from the specimen edge. The red arrows in (a) show the FIB milling direction.