Low temperature plasma process based on CO-rich CO/H2 mixtures for high rate diamond film deposition

A low temperature process (350 °C<T<500 °C) for nanocrystalline diamond film growth by microwave plasma-enhanced chemical vapor deposition has been developed that yields high rates (up to 2.5 μm/h) at relatively low plasma powers (0.5 kW). In contrast to the widely used H2-rich mixtures of CH4 or CO and H2 that exhibit monotonic decreases in the diamond growth rate as T is reduced from 800 to 400 °C, CO-rich mixtures of CO and H2 exhibit an increase and sharp maximum as T is reduced. The results suggest a different diamond growth mechanism from the CO-rich mixtures.