Atom probe specimen preparation and 3D interfacial study of Ti–Al–N thin films

3D-atom probe tomography is used to study the atomistic morphology of Ti–Al–N thin films in the as-deposited and annealed states. We present results on modification of a focused ion beam based lift-out technique to meet the challenges for specimen preparation of substrate-free thin film material, which allows to avoid substrate interference during post-deposition annealing. We further emphasize the influence of doped silicon and low-carbon steel posts on the measurement performance during atom probe tomography of Ti0.46Al0.54N films. Pre-sharpened silicon posts ensure the preparation of equally shaped specimens, whereas steel posts reach a better mass resolution. Taking these results into account, we moreover examined the decomposition of Ti0.46Al0.54N towards TiN and AlN with respect to determination and distribution of oxygen impurities as a function of temperature. Thereby we observe an enrichment of these oxygen impurities in AlN with increasing annealing temperature to 1350 °C, from an originally random distribution in the as-deposited state.