Effect of nitrogen addition on the properties and thermal stability of fluorinate amorphous carbon films

Continuous fluorinated amorphous carbon (a-C: F) films doped with nitrogen (a-C: F: N) were deposited by plasma enhanced chemical vapor deposition using CF4 and C2H2 gases as precursors with the addition of N-2 gas. The surface morphologies, chemical compositions, deposition rates, thermal stability and mechanical properties of these films varied with the deposition parameters, including CF4 and N-2 feed gas concentrations, processing pressure, plasma power and substrate temperature. With increasing N-2 feed gas concentration, the nitrogen content of the a-C:F:N films increased to about 6 at.% and contributed to higher mechanical properties. After thermal annealing, the a-C: F films with higher fluorine contents exhibited more obvious fluorine release and extensive film thickness shrinkage, whereas the a-C:F:N films with higher contents of nitrogen doping yielded less composition variations, smaller thickness shrinkages, higher mechanical properties, and conclusively better thermal stability. (c) 2005 Elsevier B.V. All rights reserved.