Ultra-thin carbon layer for high density magnetic storage devices
Storage density is presently doubling every year. This requires the read head to approach closer to the magnetic layer, and ever-thinner layers of carbon. Film thickness below 2 nm and roughness well below 1 nm are needed for the storage of ~1 Tb/in2. Here we present an analytical and functional characterisation of ultra-thin carbon nitride and pure carbon films produced by magnetron sputtering and filtered high current vacuum arc. The main focus is the effect of nitrogen com position and decreasing film thickness on the relevant mechanical and tribological properties. The carbon bonding has been monitored by using a combination of Raman spectra, taken at two wavelengths (514 and 244 nm). We show that the density, nitrogen content, scratching resistance and Young's modulus of ultra-thin films can all be monitored by the G peak dispersion. Also, the G peak full width at half maximum is a useful parameter in order to investigate the structural evolution of thin films.