Cubic boron-nitride (c-BN) films were deposited on a silicon substrate by varying the deposition time, using a reactive ion-plating method. In order to investigate the growth mechanism of c-BN films, these c-BN films were characterized by x-ray emission spectra of boron (B K x-ray emission spectra), infrared absorption spectra, selected area diffraction patterns, and TEM microstructures. It was found that the BN film with sp2 bonding formed initially on the substrate and subsequently c-BN film formed. The c-BN film was composed of fine crystallites with a size of about 10 nm and with random orientation. In the case of the B K x-ray emission spectrum from the BN film with sp 2 bonding, the intensity of the satellite peak at the short-wavelength side was extremely stronger than that of sp 2-bonded BN-like turbostratic or hexagonal BN. As a result of calculation of the B K x-ray emission spectrum of BN using the discrete variational Hartree-Fock-Slater (DV-Xα) method, it was found that the satellite peak intensity increased with formation of the fine BN cluster having two-coordinated boron (which has a dangling bond) and with decreasing size of the cluster. Therefore, it is considered that the BN film with sp 2 bonding was composed of the very fine BN cluster having two-coordinated borons, and became the precursor of c-BN film at the interface between the substrate and c-BN film.
