MECHANISMS OF THE DEPOSITION OF HYDROGENATED CARBON-FILMS

The paper reviews the elementary processes during the plasma-enhanced chemical vapour deposition of hydrogenated carbon films from methane, with special emphasis on the surface processes which determine the growth rate and film structure. Corresponding model calculations are critically discussed in comparison to experimental findings. Whereas a simplified plasma modeling can be performed with some reliability, only very limited information is available on the the surface physical and chemical mechanisms determining the growth rate as well as the stoichiometry and the structure of the deposited films. Proposed surface models involving widely different processes yield similar results and are thus indiscernible in comparison to results from deposition experiments. Nevertheless, reasonable fits to growth data can be obtained using a combined plasma-surface model. For the formation of film structure, recent ellipsometric data indicate that hydrogen chemistry might play a decisive role in addition to or rather than ion collisional effects.