Effects of low-dose Si implantation damage on diffusion of phosphorus and arsenic in Si

The effects of low-dose Si implantation damage on diffusion of low-concentration P and As in Si wafers are investigated. Dopants are implanted at a low dose and subsequently preannealed to remove any self-damage. An enhanced diffusion of P is observed by directly comparing dopant profiles in damaged and undamaged regions. Monitoring effective diffusivity of P at various annealing temperatures and times reveals that the enhanced diffusion is a transient process with a time constant which is larger at lower temperature. This enhancement is larger and of longer duration the lower the annealing temperature is. In contrast to P, As diffusion in the damaged region does not show any enhancement. This implies that the defects induced by the Si implants have separate mechanisms for interaction with each type of dopant.