In order to investigate the effect of the self-bias voltage applied to a substrate on the formation of cubic boron nitride (c-BN) film, boron nitride (BN) films were deposited on silicon wafer by varying the self-bias voltage, using the reactive ion plating method with a hot cathode plasma discharge in a parallel magnetic field. The crystal structures of these BN films were identified by characteristic X-ray emission spectra of boron measured with an EPMA and infrared absorption spectra.
The self-bias voltage in excess of-15 V must be applied to a substrate for the formation of c-BN film. But c-BN film grows independently of the self-bias voltage about 5 minutes after starting the deposition. Therefore, c-BN film can be deposited without excessive ion bombardment by dropping the self-bias voltage during the deposition. The deposition rate of BN film decreases with an increase in the self-bias voltage. It is effective for the increase of its deposition rate to drop the self-bias voltage after the initial period of the deposition.