Effects of Si impurity on the nucleation and growth of cubic boron nitride thin films

The incorporation of silicon into boron nitride thin films has been achieved by a negatively biased thin silicon rod being inserted into plasma during thin film growth in ultrahigh-vacuum sputtering. X-ray photoelectron spectroscopy and secondary ion mass spectroscopy indicated that the Si concentration and profile in the thickness direction were successfully controlled by changing the position of the rod during film growth. The deposition resulted in the formation of turbostratic boron nitride (tBN) when 4.4 at.% Si was incorporated before cBN nucleation. On the other hand, the cubic phase was formed when the same amount of Si was added after the nucleation. These results suggest that the amount of silicon impurities that suppresses cBN nucleation is less than that suppresses cBN growth.