BF2+ implantation through a sacrificial oxide for the formation of p(+)/n shallow junctions is frequently applied in device fabrication. The effects of fluorine on boron diffusion in and out of a silicon substrate during nitrogen-ambient high temperature rapid thermal annealing have been studied. By comparing B and BF2 implanted substrates, it is shown that fluorine out-diffusion during high temperature annealing coincides with enhanced boron out-diffusion into the oxide and suppressed boron diffusion into the substrate. In particular, when fluorine accumulated at the end of range dislocation loops is driven out of the bulk, shallower junctions are observed.