Electrical characteristics and growth kinetics in discharges used for plasma deposition of amorphous carbon

Abstract

This paper is concerned with the electrical characteristics of low frequency (50 kHz) and high frequency (13.56 MHz) discharges used for the deposition of amorphous hydrogenated carbon thin films from CH 4, C 6H 6 and theeir mixtures with helium gas. It is shown that the pressure P and either the current density at low frequency J or the self-bias voltage V B at high frequency are the major macroscopic parameters controlling the deposition. The growth kinetics were studied and the mass deposition rate was found to be a quasi-linear function of P 1 2 . The effects of ion bombardment are related to the products V BP −1 2 (13.56 MHz) and JP 1 2 (50 kHz), the inverse square root dependence for the pressure arising from the quasi-linear evolution of the sheath thickness with P −1 2 . This ion bombardment results in film densification. The relations between structure, properties and ion fluxes will be reported in a forthcoming publication.