Activation and Deactivation of Implanted B in Si

The temporal evolution of the electrically active B fraction has been measured experimentally on B implanted Si, and calculated using atomistic simulation. An implant of 40 keV, 2x10 sup (14) cm sup (-2) B was examined during a post-implant anneal at 800C. The results show a low B activation (~25%) for short anneal times (= 10 seconds) that slowly increases with time (up to 40% at 1000 seconds), in agreement with the model proposed by Pelaz et al. [Appl. Phys. Lett. 70, 2285 (1997)]. Based on the results, we conclude that B clustering occurs in the presence of a high interstitial concentration, in the very early stages of the anneal. For this reason, B clustering is not avoided by a short or low-temperature anneal. The total dissolution of B clusters involves thermally generated Si interstitials, and, therefore, requires long or high-temperature anneals.