A MECHANISM OF CVD DIAMOND FILM GROWTH DEDUCED FROM THE SEQUENTIAL DEPOSITION FROM SPUTTERED CARBON AND ATOMIC-HYDROGEN

We describe a growth mechanism of CVD diamond films consisting of a se ries of surface reactions. It is derived from experimental observation s of a sequential deposition process in which incident carbon flux and atomic hydrogen flux were independently varied. In this sequential pr ocess, film growth rate increased with atomic hydrogen exposure, and a saturation in the utilization of carbon was observed. These features are consistent with a surface growth process consisting of the followi ng steps: (i) the carburization of the diamond surface, (ii) the depos ition of highly disordered carbon on top of this surface, (iii) the et ching of disordered carbon by atomic hydrogen, (iv) the conversion of the carburized diamond surface to diamond at growth sites by atomic hy drogen, and (v) the carburization of newly grown diamond surface. The nature of the growth sites on the diamond surface has not been determi ned experimentally, and the existence of the carburized surface layer has not been demonstrated experimentally. The surface growth mechanism is the only one consistent with the growth observed in conventional d iamond reactors and the sequential reactor, while precluding the neces sity of gas phase precursors.