INVESTIGATION OF THE ADDITION OF NITROGEN-CONTAINING GASES TO A HOT-FILAMENT DIAMOND CHEMICAL-VAPOR-DEPOSITION REACTOR

We have investigated the effect that addition of various nitrogen-cont aining gases, such as ammonia, methylamine and HCN, has on the composi tion of the films deposited in a standard hot filament diamond chemica l vapour deposition reactor. Total process gas concentration (C + N) w as maintained at 1% in H-2 throughout the experiments. When using a fe edstock of methane and ammonia, we generally find that for methane-ric h mixtures diamond films are formed; for ammonia-rich mixtures, silico n nitride is formed by reaction of the ammonia with the Si substrate; for approximately equal ratios of CH4 to NH3, little film deposition o ccurs. Other gases, such as CH3NH2 and HCN, behave similarly to 1:1 mi xtures of CH4 and NH3. Results are explained in terms of a simple chem ical model of the gas phase chemistry and surface interactions.