Composition and diffusion of nitrogenated carbon into the magnetic layer

Abstract

A series of dc sputter deposited amorphous carbon nitride films were characterized by micro-Raman spectroscopy. Films were deposited on silicon, CoCrPt/CrV/glass and a CoCrPtTa/CrV/glass substrate. A direct correlation was found between the nitrogen content in a film, measured by Rutherford backscattering spectroscopy, and the Raman C≡N peak intensity. A frequency downshift of the Raman G band was observed for very thin films. It reflects not only the film structure but also the contribution from the vibration spectrum of the film-substrate interface. From the integrated intensity of the carbon band and a Raman shift it is possible to determine the thickness of the carbon overcoat as well as evaluate the carbon diffusion into the magnetic layer. A secondary ion mass spectroscopy carbon depth profile analysis provided additional proof of carbon diffusion into the magnetic layer.