Wafer samples were implanted with 1keV 11B+ and 5keV BF2+ to a dose of 1015/cm2 at a tilt angle of 0º. The samples had been pre-amorphized by 70keV Si+ implantation to a dose of 1015/cm2. They were rapidly thermally annealed (less than 0.1s, 1000 or 1050C) in an ambient of 33ppmO in N2 in order to investigate the effect of F (from BF2) on transient enhanced diffusion. By using a relatively deep pre-amorphization of 145nm, any difference in damage between amorphizing BF2 implants and non-amorphizing B implants was eliminated because the entire profile (less than 80nm after annealing) was well within the amorphous layer. During annealing, a back-flow of interstitials from the end-of-range damage due to pre-amorphization produced transient enhanced diffusion of B in the re-grown layer. This permitted the chemical effect of F on B transient enhanced diffusion in re-grown material to be studied independently of the effect of damage. Secondary ion mass spectroscopy showed that, during annealing, the presence of F reduced the amount of B diffusion by 30% (1000C) or 44% (1050C). This demonstrated that there was a marked effect of F on B transient enhanced diffusion, independent of the effects of implantation damage. A temperature dependence of the enhancement factors suggested that transient enhanced diffusion rather than B-treatment was the source of interstitials.

Effect of Fluorine on the Diffusion of Boron in Ion-Implanted Si. D.F.Downey, J.W.Chow, E.Ishida, K.S.Jones: Applied Physics Letters, 1998, 73[9], 1263-5