The effects of substrate bias voltage and radio-frequency power on the growth of c-BN phase coatings

Films containing cubic boron nitride (c-BN) were deposited on Si(100) substrates from a hexagonal boron nitride (h-BN) target with a conventional sputter device by using a two-stage deposition process. Preferentially oriented h-BN layers were first deposited with a radio frequency (RF) power of 600 W at the substrate negative bias voltage of 100 V for 10-15 min, and then followed by the deposition of c-BN films with an RF power of 150 W to 640 W at different substrate negative bias voltages ranging from 0 to 180 V for 150 min. The films were examined primarily by transmission Fourier transform infrared spectroscopy. For the first time, it was found that films containing c-BN phase could be prepared by using a two-stage deposition process with no negative bias voltage applied to the substrate during the second stage. The dependences of the fraction of c-BN on the substrate negative bias voltage and the RF power were investigated. The results indicate that increasing RF power leads to an increase in the fraction of h-BN, while the substrate bias voltage facilitates the formation of c-BN and suppresses efficiently the growth of h-BN. (C) 1999 Elsevier Science S.A. All rights reserved.