In the present study we have modeled the diffusion of boron in single crystal silicon from an ion-implanted polysilicon film deposited on a single crystal silicon substrate. Modeling has been done for both BF2 and boron implants in the polysilicon layer. A new phenomenological model for a diffusivity has been implemented in the PEPPER simulation program using an effective concentration-dependent diffusivity approach. The effective diffusivities of boron in single crystal silicon have been extracted using Boltzmann-Matano analysis. The modeling has been implemented for a wide range of furnace anneal conditions (800°C to 950°C, from 30 min. to 6 hours), and implant conditions (BF2 doses varied from 5×1015 to 2×10'16 cm-2 at 70 keV, boron dose of 5×1015 cm-2 at 20 keV).