Plasma deposition of a-C:H, F thin films from H2-C2F6 fed RF glow discharges

Abstract

Thin films have been deposited from 0-20% C2F6-H2 fed radiofrequency (RF) glow discharges in a triode reactor. Deposits contain carbon, hydrogen and fluorine in a variable extent, and can be classified as a-C:H, F materials. The effects of feed composition, substrate temperature and substrate bias on the overall deposition process and on the chemical composition of the films have been studied. Actinometric optical emission spectroscopy has been utilized as a diagnostic tool of the plasma, while the film composition has been investigated by means of electron spectroscopy for chemical analysis. A deposition mechanism is proposed which involves carbon atoms and CH radicals as film precursors, and fluorine atoms as responsible for the material fluorination. The net deposition rate is the result of competition between deposition kinetics and ablation steps, all steps being assisted by ions.