Growth and bonding structure of hard hydrogenated amorphous carbon thin films deposited from an electron cyclotron resonance plasma

Analysis of hard hydrogenated amorphous carbon films (a-C:H) deposited from an electron cyclotron resonance radio frequency discharge of methane–argon (5%) mixture at low pressure is reported. The properties of films were determined in their as deposited state using elastic recoil detection analysis, infrared absorption, Raman spectroscopy, transmission spectroscopy, photothermal deflexion spectroscopy, and residual stress measurements. The microstructural changes (i.e., hydrogen content and C-sp³/C-sp² ratio) have been explained qualitatively in terms of a balance between implantation and relaxation processes. A good correlation is observed between the variation of Raman features and the optical gap as a function of the self-bias substrate. The residual stress versus bias plot shows behavior similar to that already obtained for tetrahedral amorphous carbon films and the optimum energy, which corresponds to films of maximum C–C sp³, is similar to those obtained in the literature. © 2002 American Institute of Physics.