Boron-interstitial silicon clusters and their effects on transient enhanced diffusion of boron in silicon

The nature of ion-implantation induced clusters of boron and silicon-self i nterstitials (BICs), and their effects on transient enhanced diffusion (TED ) of B in Si have been investigated in samples predoped with B at different concentrations. Excess Si interstitials have been introduced by Si+ implan tation at 60 keV with doses of 1 and 5x10(14) cm(-2). The B diffusivity and the amount of B trapped in the clusters have been evaluated from the best fits of simulation-prediction profiles to experimental B profiles, after an nealing at 740 and 800 degrees C for different times. Our results show that the BICs in the beginning act as a sink for interstitials, strongly reduci ng the TED in the early phases of the annealing. However, being more stable than the Si-interstitial clusters and the {113} defects, they dissolve slo wly and can, therefore, sustain a moderate Si-interstitial supersaturation for longer annealing times, even when the Si-interstitial defects are compl etely dissolved. The data show that the amount of B in the BICs is higher t han that of the interstitials; we estimate an average ratio between the B a nd interstitial concentrations to be about 1.5. (C) 2000 American Institute of Physics. [S0021- 8979(00)01521-8].