In this work the authors study the interaction of F with point defects and the influence of F on B diffusion in crystalline Si. The authors perform 25 and 100 keV F+ implants and combine them with a 40 keV Si+ implant. The appearance of peaks in the F profile during annealing supports the idea of the formation of F complexes with vacancies and Si interstitials. In all samples implanted with F+ analyzed in this work, B diffusion is higher than in equilibrium conditions indicating that F+ implants in crystalline Si produce a Si interstitial supersaturation. However, B diffusion is reduced when F+ is coimplanted with Si, compared to only Si implants. This effect is more evident when B is located in the region where the F+ implant generates an excess of vacancies, but it also appears in the Si interstitial-rich region. The results indicate that the effect of F on B diffusion in crystalline Si is time dependent. (C) 2008 American Vacuum Society.