Characterization of metal-containing carbon films using Raman scattering

Abstract

Metal-containing carbon (Me-C:H) films were deposited using the electron cyclotron resonance chemical vapor deposition technique in conjunction with a metal screen-grid system. Four sets of Me-C:H films were analyzed using Raman scattering. Two sets were molybdenum-containing carbon (Mo-C:H) films deposited at fixed dc bias (at different CH4/Ar ratios), and at fixed CH4/Ar ratio (at different dc bias). Another two sets of nickel-containing carbon (Ni-C:H) films were deposited at fixed rf power, but at a different CH4/Ar ratio, with and without postgrowth thermal annealing at 200 °C. All films showed the characteristic G and D peaks except for those with high metal content. The D peak is very pronounced in the Ni-C:H films, and both the G and D peaks follow an opposite trend; downshifting and upshifting in wave number, respectively, as the CH4/Ar ratio was increased. In the case of Mo-C:H films deposited at fixed dc bias, both peaks downshifted in wave number, following an increase in the CH4/Ar ratio. The G peak full width at half maximum for both the Ni- and Mo-C:H films increased slightly with an increase in CH4/Ar ratio, consistent with the variation in the relative integrated intensity of the D to G peak (ID/IG). Thermal annealing experiments conducted on the film samples revealed relatively stable characteristics with a minor effect on the film structure. The results showed that the impinging ion energy plays an important role in the structural properties of the Me-C:H films.