THE INFLUENCE OF BIAS ON GASEOUS COMPOSITION AND DIAMOND GROWTH IN A HOT-FILAMENT CHEMICAL-VAPOR-DEPOSITION PROCESS

In situ optical emission spectroscopy has been used to measure the dir ect current biased hot-filament diamond deposition processes for gas m ixtures of methane, argon and hydrogen. The effects of bias on diamond growth and optical emission were investigated. The increase of bias v oltage slightly raises the atomic hydrogen concentration which is esti mated by using the Ar (750 nm) line as actinometry. The bias has littl e influence on hydrocarbon species and electron temperature. The enhan cement of diamond nucleation and smoothing of the film surface by posi tive bias are mainly caused by electron bombardment on the surface of the substrate and growing film rather than on the change of gaseous en vironment.