Deposition of DLC films in CH4/Ar and CH4/Xe rf plasmas

The deposition of hydrogenated diamond-like carbon (DLC) film and plasma diagnostics were carried out in 13.56 MHz radiofrequency CH4/Ar and CH4/Xe plasmas. The film deposition rate use the CH4/Ar plasma decreased gradually with decreasing CH4 content until the latter reached 10%, after which it decreased rapidly. However, in CH4/Xe plasma a marked decrease in the deposition rate was observed as the CH4 content was reduced to about 80%. In mass spectrometry measurements, it was found that the addition of Ar to CH4 plasma enhanced the hydrocarbon ion density, whereas addition of Xe resulted in a decrease in the ion density and a simultaneous increase in the CH3 radical density. These results for the film deposition rate and the mass spectrometry measurements suggest that the film deposition rate is determined by reactions of predominant CH3 radicals with hydrocarbon ions on the growing film surface. The mechanical hardness and the IR absorption spectrum of the film were also measured.