Characterization of diamond deposition from chloromethane reactants by laser reflective interferometry

Laser reflective interferometry (LRI) was employed to compare the nucleation and film growth characteristics of diamond deposition between methane and chloromethane reactants. LRI has the capability of in situ monitoring of the film-forming stage and the film growth stage. During the film-forming stage deposition behavior involves the nucleation and subsequent growth of discrete diamond crystallites. During the film growth stage, it involves the growth of a continuous film. In comparison to methane reactant, chloromethane was observed to enhance slightly the growth rate during the film growth stage by 7%, 16%, and 39% at substrate temperatures of 850, 750, and 650°C, respectively. However, chloromethane reduced the time required for film formation and increased the nucleation densities significantly, particularly at low growth temperatures. The reason that chloromethane enhances the total growth rates at low temperature is mainly due to its ability to stabilize diamond nucleus precursor and thus enhance diamond nucleation.