SYNTHESIS OF CUBIC BORON-NITRIDE THIN-FILMS

An equilibrium thermodynamic analysis of the Gibbs free energy in a no n-hydrostatic stress field is applied to the formation of boron nitrid e thin films. The theory predicts a specific sequence of microstructur es from non-oriented hexagonal boron nitride, through oriented hexagon al boron nitride and finally cubic boron nitride. It also predicts a t hreshold stress for cubic boron nitride formation. These predictions a re in agreement with experimental observations reported here and made by others. The synthesis of cubic boron nitride in a new helicon wave plasma source is demonstrated. The operating parameters which produce the cubic phase are determined.