Reduction of boron thermal diffusion in silicon by high energy fluorine implantation

A study was made of the effect of ahigh energy F+ implant on the thermal diffusion of boron from a shallow marker layer grown by molecular beam epitaxy (MBE) and annealed for 30s at 1000°C. Fluorine SIMS profiles show a broad fluorine peak in the vicinity of the boron profile, and a deeper peak just beyond the range of the fluorine implant. An explanation for the boron thermal diffusion suppression was proposed in which the fluorine increases the excess vacancy concentration in the vicinity of the boron profile due to the formation of fluorine-vacancy clusters, and hence creates an undersaturation in the interstitial concentration.