AFM observations of DLC films prepared by the ECR sputtering method

Diamond-like carbon films were deposited onto glass substrate in an Electron Cyclotron Resonance (ECR) plasma with a graphite target and an Ar-O-2 process gas. The effects of target voltage, substrate potential, gas pressure, oxygen content were evaluated as process parameters. The surface morphology of the deposited films was observed with an Atomic Force Microscope (AFM). The electrical conductivity and optical transmittance of deposited films are dependent on the oxygen content in the profess gas. The deposited films, made in condition under 10 mol% in oxygen content, are conducting and 50% in transmittance. Above 20 mol% in oxygen content, they are nonconducting and 80% in transmittance. The films are composed of mixtures of sp(2) and sp(3) carbon. This was evaluated with Raman spectroscopy. The surface morphology, observed with AFM, shows coagulated micro-crystals of under 20 nm size for a substrate temperature of 400 degrees C. The details of the properties and the surface morphologies in the initial growth stages of DLC films prepared by ECR sputtering technology are discussed.