Comparison of atom probe compositional fidelity across thin film interfaces

Abstract

A series of Fe/Ni and Ti/Nb multilayered thin films with bilayer repeat distances of approximately 4nm were sputter-deposited onto n-doped Si [001] substrates. The films were then focus ion beam milled into the needle-shaped geometry required for atom probe analysis in two different orientations—one with the chemical interfaces oriented parallel to the evaporation direction and the other perpendicular to the evaporation direction. The atom probe reconstructions' compositional profiles were compared between each field evaporation orientation and to a compositional profile acquired using electron energy-loss spectroscopy (EELS). The influence of geometric field factor, image compression factor, and density smoothing parameters on the atom probe reconstructions were compared to the EELS data. Local magnification artifacts in the atom probe reconstructions were identified and were especially evident in the case when the interfaces are field evaporated parallel to the evaporation direction.