Comparative study of the effect of thermal annealing on the hydrogen stability and the stress in a-C:H films deposited by electron cyclotron resonance glow discharge and direct current multipolar plasma methods

The effects of thermal annealing on the hydrogen stability and stress in two types of a-C:H films were measured. The films were prepared in a dual electron cyclotron resonance radiofrequency glow discharge or in a direct current multipolar plasma system from pure methane, at substrate bias voltages of −30 and −600 V for each type of film. Infrared absorption, elastic recoil detection analysis and internal stress measurements are used to measure some properties of the films in the as-deposited state and after annealing at increasing temperature up to 700°C. The results indicate that the two types of samples have completely different magnitudes of stresses in their as-deposited state, and that they have also different H thermal stabilities. The stresses are also affected differently by annealing. Annealing reduces the magnitude of the stresses in all cases. For annealing temperature >400°C, and for the −600 V substrate bias, the stress relaxation occurs through atomic rearrangement in the direct current plasma deposited films, while it induces a loss of adhesion in the glow discharge samples.