The presence of a supersaturation of Si self-interstitials in ion-implanted material was shown to be the cause of the transient enhanced diffusion of B, of the formation of extended defects at the projected range of implanted atoms (at doses below the amorphization threshold), and of the formation of end-of-range defects in the case of a pre-amorphization stage. The relationship between anomalous B diffusion and end-of-range defects was considered. Modelling of the behavior of these defects during annealing revealed how they affected dopant diffusion. This was possible via a development of Ostwald ripening theory, as applied to extrinsic dislocation loops. This theory treated variations in the mean supersaturation of Si self-interstitial atoms between loops, and also explained anomalous diffusion. The initial supersaturation before annealing was at least 5 decades larger than the equilibrium value, and decayed exponentially with time during annealing. The activation energies were the same as those involved in transient enhanced diffusion. It was shown that this time decay was the basis of the transient enhancement of B diffusivity, via the interstitial component of B diffusion. Other experiments clarified the effect of the proximity of a free surface upon the thermal behavior of end-of-range defects, and permitted the quantitative description of the spatial and temporal evolution of B diffusivity during the annealing of pre-amorphized Si layers.

Transient Enhanced Diffusion of Boron in the Presence of End-of-Range Defects. C.Bonafos, M.Omri, B.De Mauduit, G.BenAssayag, A.Claverie, D.Alquier, A.Martinez, D.Mathiot: Journal of Applied Physics, 1997, 82[6], 2855-61