Cesium-enhanced RF magnetron deposition of carbon nitride and diamond-like carbon films

We report the design, manufacturing, and testing of a new cesium enhanced negative carbon ion source that can be useful to synthesize hard and/or electron emitting carbon nitride and diamond-like carbon (DLC) thin films. The design of the source includes a conventional magnetron-sputtering gun, low voltage ion extraction lenses, and a cesium oven to provide cesium vapor for formation of a fractional monolayer of Ca on the carbon target. Cs reduces the surface work function of the carbon target and enhances the emission of negative carbon ions. Argon and argon-nitrogen gas mixtures were used to ignite and sustain the plasma in the chamber. We compare the properties of carbon nitride and DLC films deposited with and without cesium. Nitrogen composition in the Ar-N-2 gas mixture was observed to be an important process parameter affecting mechanical properties of the film. The effect of the Cs oven temperature on deposition rate and current absorbed at the substrate was also investigated for RF powers from 0 to 150 W.