The transient enhanced diffusion of B in silica, after low-energy B implantation and annealing, was investigated by using B-doping superlattices which had been grown by means of low-temperature molecular beam epitaxy. The 5, 10, 20 or 40keV B ions were implanted to a dose of 2 x 1014/cm2. Subsequent annealing was carried out (750C; 180s, 0.25h or 2h) in a N ambient. Broadening of the B spikes was measured by using secondary ion mass spectroscopy. The enhancement of B diffusivity was determined as a function of the implantation energy. The transmission electron microscopic results showed that <311> defects were seen only for implantation energies that were greater than 10keV at the given dose, and that the density increased with implantation energy. The doping superlattice studies indicated that the point defect concentration in the background decayed much slower when <311> defects were present. These results implied that there were at least 2 causes of the transient enhanced diffusion of implanted B. One was a short-term component that rapidly decayed in a manner which was consistent with non-visible implanted B pairs, and the other was a longer-term component that was consistent with interstitial release from <311> defects.

The Effect of Boron Implant Energy on Transient Enhanced Diffusion in Silicon. J.Liu, V.Krishnamoorthy, H.J.Gossman, L.Rubin, M.E.Law, K.S.Jones: Journal of Applied Physics, 1997, 81[4], 1656-60