FIB damage of Cu and possible consequences for miniaturized mechanical tests

Cu specimens were exposed to Ga+ ion bombardment for varying conditions of ion energy, ion dose, and incident angle in a focussed ion beam workstation. Conventional transmission electron microscopy investigations were employed to analyze the Ga+ ion induced damage. The extent of visible damage was minimized by reducing the ion energy and furthermore by using grazing incident ions. Concentration depth profiles of the implanted Ga were measured by Auger electron spectroscopy. Concentrations of up to 20 at.% Ga were found several nanometers below the surface. Ga contents of more than 2 at.% were detected within a depth of up to ∼50 nm. Mechanical consequences in terms of possible hardening mechanisms are discussed, taking into account the experimental findings along with Monte Carlo simulations. A non-negligible influence of the ion damage is predicted for submicron-sized samples.