Precision FIB TEM Specimen Preparation ‘at a Distance’

Extract

There is a trend in electron microscopy towards centralization of the more sophisticated EM systems. The rationale is that the techniques associated with such instrumentation are more efficiently practiced and developed by dedicated specialists in a regional or national centre surrounded by an extensive infrastructure. A similar argument can be used for the preparation of TEM specimens, especially as the demand grows for more precise location of the thin area to be examined. A new trio of techniques - tripod polishing, ultramicrotomy, and focused ion beam (FIB) thinning - can locate the thin area to within a micron or less. In the first two, a linear feature first located via light or scanning electron microscopy can be cross-sectioned by controlled material removal via mechanical polishing or diamond knife sectioning, respectively. With FIB, feature location and material removal are carried out in-situ, first imaging with a low intensity beam, then milling trenches on either side of the feature with a high intensity beam that is decreased as the feature is approached.