Magnetic properties of Co-N films deposited by ECR nitrogen/argon plasma with DC negative-biased Co target

By introducing DC negative-biased Co target in the Electron Cyclotron Resonance (ECR) nitrogen/argon plasma, the Co-N films containing Co4N phase were synthesized on Si(100) substrate. Effects of processing parameters on magnetic properties of the films are investigated. It is found that magnetic properties of Co-N films vary with N2/Ar flow ratio, substrate temperature, and target biasing voltage. The saturation magnetization Ms decreased by increasing the N2/Ar gas flow ratio or decreasing target biasing voltage, while the coercive field Hc increased, which is ascribed to the variation of relative concentration for N or Co active species in plasma vapor. The magnetic properties present complex dependency with growth temperature, which is related to the atom mobility on the substrate affected by the growth temperature. This study exhibits a potential of ECR plasma chemical vapor deposition to synthesize the interstitial compounds and tune magnetic properties of films.