Axial distribution of emission and rate of deposition of diamond-like film in r.f. discharges in CH 4

Abstract

Spatial distribution of the deposition rate of diamond-like thin films inside a r.f. discharge was studied experimentally. A thin optical fiber was inserted along the axis of the discharge which made negligible perturbation on the discharge itself. Deposited film thickness along the fiber was determined by using a scanning electron microscope and uniform and stable films up to 24 μm thick were made over periods of up to 19 h. The spatial distribution of deposition resembled the diffusion profile and from the comparison of its second derivative and the spatial distribution of emission it was found that the deposition precursor does not react with the ground-state molecules. From the analysis of available chemical kinetics and transport data for methane discharges it was found that the deposition precursor is CH 3 radical. Spatial distribution of emission was obtained using a CCD camera with interference filters.