One of the most important processes for ULSI devices is the formation of shallow junctions. Many technologies using laser processing have been developed to recover crystal defects and activate implanted ions in silicon. We propose a novel technology for recovery of crystal defects in silicon at low temperature in comparison with the conventional thermal process by using coherent lattice vibration with high energy, which is excited in the silicon due to absorption of mid-infrared light and multi phonon generation in the silicon substrate. In this paper, we report that the crystal defects which were introduced by the As ion implantation in the silicon substrate can be recovered by laser irradiation with wavelength of 16.4 pm using a Free Electron Laser (FEL). We also discuss how the recovery mechanism is absolutely different from the conventional thermal process by nanosecond laser irradiation or non-thermal process by femtosecond laser irradiation.