Ultrathin CNx overcoats were grown using pulsed dc magnetron sputtering. Substrates were mounted on a holder that allowed 45 degrees tilt angle and rotation. Effects of process parameters on film growth were reviewed. AFM scans over large sampling areas show that thin CNx films obtained at -100 V substrate bias with 45 degrees substrate tilt and 20-25 rpm rotation have r.m.s. roughness about 0.2-0.3 nm when sampled over 20 x 20 mu m(2) areas, increasing to similar to 0.45 nm when sampled over similar to 0.05 x 3 cm(2) using X-ray reflectivity measurements. These 1-2 nm thick ultrasmooth coatings reduced corrosion damage compared with coatings of the same thickness grown without substrate tilt and rotation. This improved performance is likely a result of more efficient and uniform momentum transfer parallel to the surface during deposition in this configuration. In addition, detailed X-ray reflectivity measurements showed that the mass density of these CN., films is similar to 2.0 g/cm(3), independent of film thickness from similar to 1 to 10 nm, consistent with ion beam analysis. (c) 2005 Elsevier B.V. All rights reserved.