Turbostratic-like carbon nitride coatings deposited by industrial-scale direct current magnetron sputtering

Carbon nitride thin films were deposited by direct current magnetron sputtering in an industrial-scale equipment at different deposition temperatures and substrate bias voltages. The films had N/(N + C) atomic fractions between 0.2 and 0.3 as determined by X-ray photoelectron spectroscopy (XPS). Raman spectroscopy provided insight into the ordering and extension of the graphite-like clusters, whereas nanoindentation revealed information on the mechanical properties of the films. The internal compressive film stress was evaluated from the substrate bending method. At low deposition temperatures the films were amorphous, whereas the film deposited at approximately 380 °C had a turbostratic-like structure as confirmed by high-resolution transmission electron microscopy images. The turbostratic-like film had a highly elastic response when subjected to nanoindentation. When a CrN interlayer was deposited between the film and the substrate, XPS and Raman spectroscopy indicated that the turbostratic-like structure was maintained. However, it was inconclusive whether the film still exhibited an extraordinary elastic recovery. An increased substrate bias voltage, without additional heating and without deposition of an interlayer, resulted in a structural ordering, although not to the extent of a turbostratic-like structure.