Effect of diamond films as bufferlayer on formation of cubic boron nitride films by chemical vapor deposition

Boron nitride films are produced by the reaction of diborane (B2H6) and ammonia (NH3) in a mixture of hydrogen and argon using microwave plasma-assisted chemical vapor deposition. Some parameters as NH3/B2H6 ratios, hydrogen addition, substrate-bias voltage and working pressure are modulated to obtain high c-BN content in the film. The influence of diamond films with various grain sizes as bufferlayer on the formation of c-BN is investigated. As-grown BN/diamond films are characterized by Fourier transform infrared spectra, X-ray diffraction patterns and scanning electron microscopy. The results indicate that the nature of diamond film affects the amount of c-BN in the BN layer. Nanocrystalline diamond film can promote the c-BN formation, resulting in the c-BN content up to 85%. Thick c-BN/diamond multilayer up to 5.5 μm in total thickness and with nearly pure c-BN content is synthesized