It was recalled that B implants underwent anomalous diffusion during annealing, and that this was detrimental to ultra-shallow junction formation. The implantation-induced transient enhanced diffusion was known to be driven by the large supersaturation of self-interstitial Si atoms which was emitted from extended defects. Improved understanding had led to the development of new techniques such as C co-implantation, multiple-step annealing and point defect engineering using the co-implantation of high-energy ions. In the latter approach, high-energy ion bombardment injected vacancies near to the surface region and created excess interstitials near to the end of projected range. This manipulation of the point defects could retard B diffusion and enhance the activation of B.

Boron Diffusion in Silicon - the Anomalies and Control by Point Defect Engineering. L.Shao, J.Liu, Q.Y.Chen, W.K.Chu: Materials Science and Engineering R, 2003, 42[3-4], 65-114