Structure of nitrogenated carbon overcoats on thin-film hard disks

The compositional and structural characteristics of thin (~200 Å) carbon nitride overcoats on thin-film hard disks were studied using nuclear reaction analysis, hydrogen forward scattering (HFS), Raman spectroscopy, X-ray photoemission spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The mechanical and electrical properties of the overcoats were also measured. It was found that the structure of the overcoat depended on the nitrogen and hydrogen concentration in the films, whereas the overcoat hardness was independent of the nitrogen or hydrogen concentration, This may be due to the possibility that increased nitrogen incorporation into the overcoat does not necessarily result in an increased concentration of stoichiometric carbon nitride, which would be responsible for the overcoat hardness. The results also showed that the thickness of the bonded lubricant (Fomblin Z-DOL 2000) to the overcoat was determined by the nitrogen-to-hydrogen composition ratio in the overcoat