GROWTH-KINETICS AND PROPERTIES OF HARD AND INSULATING CARBONACEOUS FILMS GROWN IN AN RF DISCHARGE

Carbonaceous films were grown by dissociating hydrocarbon gases in an r.f. diode sputtering system. The effect of different hydrocarbon gases with various carbon-to-hydrogen ratios on the growth rate and properties of the films was investigated. A variation in the discharge frequency from 3.75 to 14 MHz did not make any significant change in the growth rate provided the power density was constant. Infrared absorption studies in the wavelength range of 2.5-50 μm on the films revealed that it was possible to obtain films which are almost transparent with a much lower r.f. power using an L-type impedance matching network between the r.f. generator and the electrode instead of a Π matching network. The films grown by the r.f. discharge technique were hard and insulating and almost transparent in the infrared but some weak absorption peaks persisted corresponding to different types of H-C bonding and it was concluded that all such bonds could not be completely broken. Rutherford backscattering (RBS) analysis of the films by 2 MeV 4He+ and 0.9 MeV protons showed that the films can contain as much as 25 at.% H. The RBS studies also revealed that the oxygen content in the films due to background gases was dependent on the power density at the target electrode and on the pressure. © 1979.