Plasma deposition of carbon layer: Correlations between plasma parameters, film structure and properties

摘要

The links between plasma parameters, discharge, film structure and properties are not really yet understood for amorphous hydrogenated carbon layers (a-C:H) plasma deposition. Here, a-C:H layers are deposited in a dual radio-frequency-multipolar microwave plasma excited by distributed electron cyclotron resonance reactor at low CH_4 pressure. This study deals with the plasma analysis, the film characterization and with plasma parameters effect on a-C:H films deposition, structure and properties. The discharge analysis shows that CH_4 is decomposed in CH_(y1)+H radicals and that C_2H_(2y2) are present in the discharge. As at low pressure, recombination can only take place on the surface, C_2 H_(2y2) desorbs from the surface. Moreover, C_2 species are observed attributed to C_2 H_(2y2) dissociation. The evolution of film composition with plasma power shows that the proportion of sp~2 CC decreases in contrast with those of CH bonds which increases. From these observations, a phenomenological model for a-C:H deposition can be proposed. Finally, properties are con-elated with the film structure and the effect of MW plasma power can then be given.