Defect evolution in ion implanted c-Si at the submicrosecond time scales during a laser thermal annealing process is investigated by means of kinetic simulations. Nonmelting, melting, and partial melting regimes are simulated. Our modeling considers irradiation, heat diffusion, and phase transition together with defect diffusion, annihilation, and clustering. The reduction in the implantation damage and its reorganization in defect aggregates are studied as a function of the process conditions. The approach is applied to double implanted Si and compared to experimental data, indicating a relationship between damage reduction and dopant activation.