Boron transient enhanced diffusion in heavily phosphorus doped silicon

A study has been made of B transient enhanced diffusion (TED) in heavily P-doped Si using secondary ion mass spectroscopy (SIMS) and positron annihilation spectroscopy (PAS). The P-doped silicon was implanted with boron ions of 40 keV energy to a dose of 3x10(14) cm(-2), and then annealed at temperatures ranging from 700-1000 degrees C in a N-2 ambient for varying durations. As P doping concentration increased from 3x10(19) to 1x10(20) cm(-3), boron diffusivity and the immobile boron fraction decreased. Our experimental results are inconsistent with the predictions of the Fermi-level model and suggest that the clustering between B atoms and Si interstitials should be invoked in order to explain the immobile portion of the B peak during TED.