The Influence of Plasma Excitation Frequency on the Properties of a-SiC:H Produced in a Glow Discharge Plasma

We have deposited a-SiC:H thin films from a silane-methane glow discharge plasma in a planar reactor using high (13Mhz and low (12kHz) frequency plasma excitation. Films produced at these two frequencies have significantly different properties as measured by vacuum UV reflectivity measurements, XPS, and infrared spectroscopy. Samples produced at the low excitation frequencies, where higher ion fluxes and energies are expected, have higher VUV reflectivities, higher bulk plasmon energies, and fewer IR bands due to organic fragments. In order to relate the VUV reflectivity data to the material properties, it was fitted to a simple Lorentz model using parameters taken from XPS data. We will discussour interpretation of these data and also the dependence of film properties on the reactant gas composition.