Determination of diamond [100] and [111] growth rate and formation of highly oriented diamond film by microwave plasma-assisted chemical vapor deposition

A novel method was proposed for measuring the epitaxial growth rate of diamond by microwave plasma-assisted chemical vapor deposition (MPCVD). Cubo-octahedral crystals were formed on an Si(100) wafer and were used as the substrate in the homoepitaxial growth. Growth rates of the {100} and {111} were simultaneously measured from the change in the top view size of crystals. Thus, the relative growth rate of {100} to {111} was obtained without any limitation of its value. The homoepitaxial growth rate was strongly affected by the type of diamond faces, CH₄ concentration in the gas phase, and deposition temperature. The growth rate of {100} was more dependent on CH₄ concentration than that of {111}, while the activation energy for the [100] growth was about half that for the [111] growth. These tendencies were in accord with growth mechanisms proposed for each diamond plane. Reaction conditions were optimized based on the relative growth rate of (100) to (111) planes, and a highly oriented (100) diamond film with a quite smooth surface was formed on an Si(100) wafer.