Growth of CN x/BN:C multilayer films by magnetron sputtering

Abstract

Symmetric CN x /BN:C multilayer thin films, with nominal compositional modulation periods of Λ=2.5, 5, and 9 nm were deposited by unbalanced dual cathode magnetron sputtering from C (graphite) and B 4C targets in an Ar/N 2 (60/40) discharge. The multilayers and single-layer of the constituent CN x and BN:C compounds were grown to a total thickness of 0.5 μm onto Si(001) substrates held at 225°C and a negative floating potential of ∼30 V ( E i ≈24 eV). Layer characterizations were performed by TEM, X-ray reflectivity, RBS, and nanoindentation measurements. Results show that CN 0.33 and BN:C (35, 50, and 15 at.% of B, N, and C, respectively) layers were prepared at the above conditions. It is suggested that all films exhibit a three-dimensional interlocked structure with a cylindrical texture in the film growth direction. The structure was continuous over relatively well defined and smooth CN x /BN:C interfaces. All coatings exhibit extreme elasticity with elastic recoveries as high as 85–90% (10 mN maximum load) attributed to the observed structure. However, the multilayers were stiffer and more elastic compared to that of the single-layers and thus shows promise for improved protective properties.