It was demonstrated that ultra-shallow high-concentration P profiles diffused preferentially towards the surface during annealing at 700C after recrystallization of an amorphous layer. Here, the preferential diffusion following a pre-amorphizing Ge implant, or after a self-amorphizing P implant, was observed. The phenomenon was driven by the presence and dissolution of Si interstitial defects. The greater the distance between the defect band and the high-concentration P profile, the less was the preferential diffusion for a fixed annealing time. The overall result of this effect was a P profile that was significantly more shallow and steep than after implantation.

Low-Temperature Diffusion of High-Concentration Phosphorus in Silicon, a Preferential Movement Towards the Surface. R.Duffy, V.C.Venezia, J.Loo, M.J.P.Hopstaken, M.A.Verheijen, J.G.M.van Berkum, G.C.J.Maas, Y.Tamminga, T.Dao, C.Demeurisse: Applied Physics Letters, 2005, 86[8], 081917 (3pp)