Boron nitride (BN) films were deposited by RF (radio frequency) sputtering, Hot-pressed hexagonal boron nitride (h-BN) of 4 N purity was used as sputtering target. The substrates were p-type Si(100) wafers with the resistance of (8-15) Omega cm, which were biased by negative DC voltage during deposition. The sputtering gas was the mixture of nitrogen and argon. Boron nitride films were characterized by Fourier transform infrared (FTIR) spectroscopy. It was found that the cubic boron nitride (c-BN) films could be formed at different radio frequency powers and different DC negative substrate bias. Furthermore, the c-BN films with almost pure cubic phase were successfully obtained under an appropriate radio frequency power and DC substrate bias voltage. Our results indicate that appropriate energy flow density of positive ions impinging on substrate for formation of c-BN should be necessary.