In this study, boron diffusion and activation characteristics of samples implanted with F co-implantation were studied to meet the challenge of lower sheet resistance. Samples were implanted with F co-implantation in a dose range of 0 (no F) to 5 x 10(15) cm(-2), at a fixed energy of 25 keV, followed by 950 degreesC/10 s rapid thermal annealing. It was found that although the fluorine has a negligible affect on the boron diffusion at the specified conditions, a higher F dose reduced the boron sheet resistance. Using reverse modeling, the boron solid solubility at 950 degreesC was extracted as function of the F co-implant concentration. For low fluorine doses (0-1 x 10(14)cm(-2)), the boron solid solubility is similar to that reported in the literature (9 X 10(19) cm(-3)). At higher doses, boron solid solubility increased by 25% and even 50% for F co-implantation doses of 1 X 10(15) and 5 X 10(15), respectively. We suggest that the F co-implantation terminates some of the defects created by the implantation, inactivating the defects and improving boron activation. (C) 2004 American Vacuum Society.