Growth of cubic boron nitride from vapor phase

Abstract

Both physical and chemical vapor deposition (PVD and CVD) methods for the growth of cubic boron nitride ( c-BN) have been reported. These experiments, reviewed in this article, produced a mixture of phases with some evidence of cubic materials. These materials were of limited crystallite size and perfection, much too poor to be useful for electronic devices or for hard coating applications. Using a solid boron source, NaBH 4, the preparation of c-BN by microwave plasma enhanced CVD has been investigated. When the deposition rate is low, the BN film deposited on an untreated single crystal silicon wafer, displayed a weak infrared absorption spectra for the turbostratic structure of BN. With submicron diamond powder scattered on the substrate, the BN films displayed strong infrared absorption attributable to c-BN. Transmission electron microscopy revealed that c-BN crystals, 50–100 nm in size, grew from the diamond submicron crystals. This suggests that c-BN preferentially nucleates on diamond.