The Scanning Transmission Electron Microscope (STEM) can provide images beyond Scanning Electron Microscope (SEM) capability, on samples which do not have to be prepared to the degree required for Transmission Electron Microscopy (TEM). For some applications, such as semiconductor production, speed of analysis is critical. This paper explores Focused Ion Beam (FIB) sample preparation for STEM.
The samples were prepared using an Hitachi FB-2000A FEB tool. Two analysis regions of similar thickness were cut. The rough sample was milled using a 500 pA beam and no polish cut. The smooth sample was prepared by cutting first with a 500 pA beam, and then using additional, smaller diameter beams, concluding with a 30 pA beam. This resulted in a sample surface polished to a degree similar to that used for TEM specimens. The samples were imaged in an Hitachi HD-2000 STEM at 200KeV. Transmission electron images taken at 100 kx are shown in Figure 1 of the rough sample and of the smooth sample.