Effects of substrate surface electric field on growth of cubic boron nitride films

High quality cubic boron nitride(c-BN) films were deposited by RF-magnetron sputtering on n type (100) silicon wafer. Experimental data indicate that electric field on substrate surface plays a key role in the structure and the quality of c-BN films deposited. It is found that c-BN films could be deposited stabely in a wide range of substrate bias by adjusting the intensity and distribution of electric field on the surface. Moreover, BN films with c-BN content up to 75% and good crystallinity could be obtained successfully under an appropriate negative bias and substrate temperature. Furthermore, it is also found that negative bias corresponding to peak in contents of c-BN phase shifts greatly with the difference of working pressure, but the contents of c-BN phase still can remain at above 75%. In view of this phenomenon, a reasonable explanation is reported by using the model of ion bombardment induced c-BN formation and the concept of incoming energy flow density during deposition.