Anomalous enhanced tail diffusion of B in directly bonded samples of heavily- or lightly-doped material was observed after annealing at temperatures ranging from 1000 to 1200C. As in the case of the enhanced diffusion which was commonly observed in B-implanted material during damage annealing, the enhanced diffusion in directly bonded samples was suggested to be due to mobile interstitial B species. In heavily-doped Czochralski-type material, interstitial B species could be produced via elastic interactions between excess Si interstitials and substitutional B atoms during solidification. The enhanced diffusivity, as deduced by comparing the present results with those which had been obtained for B-implanted specimens, could be described by the Arrhenius expression:

D(cm2/s) = 0.0003 exp[-2.1(eV)/kT]

W.Wijaranakula: Japanese Journal of Applied Physics 1, 1993, 32[9A], 3872-8