Atomistic kinetic Monte Carlo simulations have been performed to illustrate the correlation between the Si interstitial defects generated by ion implantation, and B diffusion and activation in Si. The amount of residual damage is not very affected by moderate dynamic anneal during subamorphizing implants. However, dynamic anneal even at room temperature significantly influences the residual damage in amorphizing implants. The efficiency of the surface as a sink for point defects affects the evolution of Si interstitial defects. They set the Si interstitial supersaturation that is responsible for transient enhanced diffusion of B and also control the formation and dissolution of B–Si interstitialclusters.