We propose a model for point‐defect‐assisted transient diffusion and activation of high‐dose boron implants in silicon. To model transient diffusion, a nonlinear equilibrium clustering model for point defects is used. The activation of boron is modeled as a Fermi‐level‐dependent transformation of inactive dopant clusters to substitutional atoms. Comparison with experimental data shows that this approach can provide a description of both rapid thermal annealing and long‐time furnace annealing steps, with an excellent predictive capability for both chemical and electrically active profiles. ©1995 American Institute of Physics.