Stress and structure profiles for chromium nitride coatings deposited by r.f. magnetron sputtering

Chromium nitride coatings were deposited by r.f. magnetron sputtering on silicon 〈100〉 substrates. By using an original method for stress profiles, the influence of the film thickness on the mechanical and structural properties of these films was studied. The characterization of the films was done by means of energy dispersive spectroscopy (EDS), wavelength dispersive spectrometry (WDS) and X-ray diffraction (XRD) analyses, scanning electron microscopy (SEM) and scanning tunneling microscopy (STM) observations were also performed. The first results showed that the stress is not homogeneous with the film thickness. Indeed, a peak of stress appears at a thickness approximately 200 nm. Moreover, the structure of the films evolves in a significant manner especially during the first stage of deposition. In the initial growth regime, the film with small crystallites preferentially grows in (200) direction. As the film thickness increases, the preferential orientation of the crystalline planes changes to (311). The films show a columnar structure with larger grains. This change of the structure goes together with the decrease of the stress and the film density.