Recent research in ultrashallow junction formation has been greatly focused on the development of various advanced annealing techniques. Flash annealing has become one of the most likely candidates to achieve the stringent junction requirements for the forthcoming generation of complementary metal oxide semiconductor devices. In this paper, we present an extensive study on the stability of highly active and ultrashallow B junction in preamorphized silicon formed by optimized flash annealing. Our results demonstrate a strong improvement in junction stability by using the multiple-pulse and pre-spike rapid thermal anneal flash annealing schemes. The deactivation of the flash-annealed junction is clearly shown to be correlated to the different levels of self-interstitial supersaturation, resulting from the release of excess silicon interstitials from the end-of-range defects. We show that optimized multipulse flash annealing could minimize the interaction between point defects and dopant atoms, enabling improvement in junction properties. (C) 2008 The Electrochemical Society.