Comparison of energetic carbon deposition processes for use as ultra-thin disk overcoats

Abstract

Three different processes, Plasma Enhanced CVD (PECVD), Ion Beam (IB), and Cathodic Arc (CA) have been used to deposit highly energetic carbon films in the 2 -10 nm thickness range in commercial, high throughput disk manufacturing tools. The deposition conditions used are typical of those required for disk manufacturing. Raman spectroscopy, I-V measurements, nanoindentation, and AFM based scratch testing have been used to characterize the structural, electrical, and mechanical properties of the films. The measured maximum hardness for the PECVD and IBD films are 28 and 25 GPa, respectively, and found to be influenced by the hardness of the softer substrates for the 70 - 120nm films available for measurement. The scratch resistance of the CAC films is ~2x the scratch resistance of the IBD films and 25% greater than the PECVD films. Addition of nitrogen to the films produced by both the PECVD and IB techniques reduces the hardness of the films. Both the Raman and I-V data suggest increasing concentrations of sp2 bonding result from these nitrogen additions.