Angle-resolved X-ray reflectivity measurements during off-normal sputter deposition of VN

VN coatings were deposited by reactive sputtering at different deposition angles χ. The thin film growth was monitored by angle-dispersive in situ X-ray reflectivity measurements. These measurements were realized using a monochromatic X-ray beam and exploiting its angular divergence. Already during deposition of the first few nm, the measurements revealed the formation of a porous coating with stable growth rate. The growth rate decreased with increasing tilt angle. The reduction was less than expected from the flux projection onto the sample surface. This can only partially be explained by the porosity increase with increasing tilt angle. SIMTRA simulations confirmed that the deposition rate is strongly influenced by the interplay between deposition geo-metry and particle transport.