Diamond films grown by millimeter wave plasma-assisted CVD reactor

Polycrystalline diamond films are deposited in a novel MPACVD reactor based on 10 kW gyrotron operating at frequency 30 GHz. The influence of increasing the operating frequency of microwaves in CVD reactor that exceeds the conventionally used frequency 2.45 GHz on diamond deposition process is discussed. Polycrystalline diamond films are grown on silicon substrates with 60–90 mm diameter. The growth rate of diamond films, their quality and morphology at wide variation of process parameters (gas pressure, substrate temperature, microwave power, methane and argon concentrations) in gas mixture Ar / H2 / CH4 are investigated. High growth rates up to 9 μm/h are obtained. The results of the diamond growth in 2.45 and 30 GHz MPACVD reactors are compared. The growth rate of diamond films in the 30 GHz reactor is shown to be 5 times greater than the growth rate in the 2.45 GHz reactor under identical process parameters.