Chromium nitride films formed by ion beam assisted deposition at low nitrogen ion energies in comparison to high energies

In ion beam assisted deposition (IBAD), apart from the relative ion irradiation intensity, which is the arrival ratio of impinging ions to deposited atoms (I/A-ratio), the kinetic ion energy Ek plays a dominant role. The energy deposited into the growing film by the ions, given by the I/A-ratio and Ek, influences the features of the film, such as the phase composition and microstructure, including crystallographic orientation. The influence of the kinetic nitrogen ion energy on chromium nitride films was investigated. Chromium was evaporated and condensed onto silicon wafers at ambient temperature. The growing film was concurrently bombarded with nitrogen ions at 1 kV acceleration voltage. The films were deposited with different chromium deposition rates. They were analyzed for their phase composition by X-ray diffraction, and for the elemental depth profile with secondary ion mass spectrometry. The results are compared with findings from earlier experiments with a high ion energy. It turns out that different ion energies yield different phase compositions of Cr/Cr2N/CrN, different preferential crystal orientations and different nitrogen distributions in depth.