Material Dependence of Sputtering Behavior During Focused Ion Beam Milling: A Correlation Between Monte Carlo Based Simulation and Empirical Observation

Abstract The focused ion beam (FIB) lift-out method is a high precision technique by which site-specific cross-section transmission electron microscopy (TEM) specimens may be rapidly prepared from virtually any material. The technique is particularly useful when the sample geometry or composition is complex (e.g., fibers, powders, composites and interfaces). In addition to the preparation of TEM specimens, FIB milling has also found widespread utility in micromachining and microfabrication applications as well as specimen preparation for scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS). As the applications of the FEB instrument continue to become more universally recognized, the need to understand the interrelationships between the target material, processing parameters, and process efficiency of the milling phenomena becomes more critical. Incident ion attack angle, target material stopping efficiency and sputtering yield, Y, are important variables governing the milling process. TRIM, a binary collision approximation Monte Carlo simulation code, is used to physically model variables that influence FIB sputtering behavior.