Characterization of reactive sputtering deposition processes of amorphous hydrogenated carbon

In this work, reactive magnetron sputtering was used to deposit hydrogenated amorphous carbon films. The target consisted of a graphite electrode. Different sputtering plasmas were created by varying the mixtures of argon (Ar) and methane (CH4). The relative Ar flows were varied over the whole range: from 100% to 0%. During the deposition process, optical emission spectroscopy was performed, in order to determine the reactive elements which are generated by the plasma and to correlate this information to the physical-chemical characteristics of the deposited film. Analysis of the obtained spectra shows that the 385 nm line, attributed to CH, shows a very similar behaviour as the deposition rate. Hence we propose that CH is the most important precursor of the deposition of hydrogenated amorphous carbon and that the deposition rate can be predicted by monitoring the 385 nm line. The 654 nm line, attributed to CH2, shows a behaviour similar to the sp(3) to sp(2) hybridation ratio and could predict this characteristic.