The effect of ion energy flux on the properties of hydrogenated amorphous carbon films

In this study the effect of varying ion energy flux on the properties of amorphous hydrogenated carbon films produced by plasma-assisted chemical vapor deposition from methane was investigated. The ion current, used to calculate the apparent ion energy flux, was measured through an orifice in one of the electrodes of the parallel plate system, using a Faraday cup. The film properties investigated include hardness, stress, methyl and methylene concentrations, and optical gap. All the observed properties vary significantly with ion energy flux and are strongly correlated with each other. As ion energy flux increases, the hardness increases, the compressive stress increases, the concentration of methyl and methylene groups decrease, and the optical gap decreases. The results demonstrate how the ion energy flux on to the film surface controls the final properties of the films.