Microstructural observation of boron nitride films synthesized by ion implantation

We report on the synthesis of boron nitride (BN) films by ion implantation and demonstrate the results of microstructural observation of the films. Bo ron films were initially prepared on single-crystal Si(100) substrates by r f sputtering. Then, 30 keV N-2(+) was implanted at doses ranging from 1 x 1 0(17) ions/cm(2) to 6 x 10(17) ions/cm(2) to synthesize BN. No substrate he ating was used in the sputtering and implantation processes. Chemical compo sition analysis of the films was carried out by Auger electron spectroscopy . Transmission electron microscopy was employed for microstructural observa tion. Mixed-phase BN, including t-BN, c-BN, w-BN and B25N, was identified i n the implanted films. The BN formation mechanism was discussed and compare d with theoretical models. The results of this work are consistent with the stress-induced BN formation-model in several aspects.