Focused Ion Beam Milling for Site Specific Scanning and Transmission Electron Microscopy Specimen Preparation

Abstract It has been shown that a focused ion beam (FIB) instrument may be used to prepare site specific cross-sectioned specimens to within < 0.1 μm for both scanning and transmission electron microscopy (SEM and TEM, respectively). FIB specimen preparation has been used almost exclusively in the microelectronics industry. Recently, FIB specimen preparation has been utilized for other materials systems and applications. A cross-sectioned SEM specimen is produced by sputtering away a trench of material from near the region of interest. Large amounts of material are sputtered using large ion beam diameters (e.g., l00’s nm) and high beam current (e.g., l000’s pA), while the final sputtering operations are achieved using smaller beam diameters (e.g., < 10 nm) and lower beam current (e.g., 10’s of pA). The SEM specimen may then be etched to reveal particular microstructural features of interest. A low magnification SEM image of a multi-layered device prepared for cross-section analysis by the FIB method is shown in FIG. 1.