Atomistic modeling of FnVm complexes in pre-amorphized Si

The co-implantation of F and B in pre-amorphized Si has been proved to be beneficial for the fabrication of ultrashallow junctions due to a remarkable reduction of B diffusion. This is attributed to the presence of fluorine-vacancy (F-V) complexes after regrowth, acting as annihilation centers for Si interstitials. Whereas the resulting F profile in the recrystallized layer can be easily determined by chemical profiling, the vacancy distribution, which has a strong influence on B diffusion, can only be indirectly estimated. In this work, atomistic simulations have been used to analyze several aspects that can affect the efficiency of F-V complexes on Si interstitials annihilation, by considering the effects on B diffusion and the evolution of F profiles. The vacancy content of the complexes, determined by the F/V ratio, and the complex size play an important role on B redistribution. The existence of a recombination barrier for the interaction of a Si interstitial and some F-V complexes, as proposed by theoretical calculations, and its influence on the Si interstitial annihilation efficiency of the complexes are also analyzed.