Growth responses of ultrathin CNx overcoats to process parameters

• DOI: 10.1016/j.tsf.2005.08.013
• Publication Date: 2005-09-06T17:19:34Z
• Authors: D.J. Li; Yip-Wah Chung
• Keywords: 02 engineering and technology; 0210 nano-technology

Ultrathin CN x overcoats were grown using pulsed dc magnetron sputtering. Substrates were mounted on a holder that allowed 45° tilt angle and rotation. Effects of process parameters on film growth were reviewed. AFM scans over large sampling areas show that thin CN x films obtained at -100 V substrate bias with 45° substrate tilt and 20-25 rpm rotation have r.m.s. roughness about 0.2-0.3 nm when sampled over 20 × 20 μm 2 areas, increasing to ∼0.45 nm when sampled over ∼0.05 × 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 x films is ∼2.0 g/cm 3 , independent of film thickness from ∼1 to 10 nm, consistent with ion beam analysis.