Cubic boron nitride thin film growth by boron and nitrogen ion implantation

Cubic boron nitride (c-BN) thin films were deposited on silicon substrates using mass separated ion beam deposition (MSIBD). In order to investigate the influence of the ion energy on the growth of c-BN films, B-11(+) and N-14(+) ions were implanted into c-BN with ion energies ranging from 5 keV to 43 keV and substrate temperatures (T-S) from room temperature (RT) to 250 degrees C. A systematic study on the interplay of E-ion and T-S has revealed a characteristic energy-dependent temperature threshold for c-BN growth. This behavior is explained by dynamic annealing of defects caused by a penetrating ion in a collison cascade. In this picture, the suppression of defect accumulation that is crucial for maintaining cubic phase formation is attributed to temperature-driven back diffusion and subsequent annihilation of B and N interstitial recoils. The model is confirmed by analyzing the depth profile of implanted, isotopically pure B-10, and its application for both c-BN nucleation and growth is discussed.