MODELING OF SUPPRESSED DOPANT ACTIVATION IN BORON-IMPLANTED AND BF-IMPLANTED SILICON

The diffusion and activation of boron following the rapid thermal annealing (RTA) of ion-implanted boron and BF2 are investigated. The early stage of RTA is characterized by the enhancement of boron diffusion and the suppression of dopant activation throughout the impurity depth profile. This phenomenon is explained and modeled by considering the reaction kinetic between the electrically activated boron species and the inactive boron-silicon interstitially. The self-interstitial supersaturation created by ion implantation damage is believed to lower the boron activation during RTA by forming electrically inactive boron interstitialcies. A model that accurately predicts both the enhanced diffusion and the suppressed activation of boron during RTA is presented.