Epitaxial silicon boride layers, when located at the surface or within the bulk of single crystals, gave rise to enhanced B diffusion during annealing. A sub-monolayer buried boride layer released 0.4 interstitials per B atom in the layer. This generated a transient diffusion enhancement, ranging from 10 to 100, for several minutes at 900C. The resultant profile-broadening was comparable to that caused by ion-implantation damage. Surface boride layers, when used at the same temperature, generated a diffusion enhancement of about 6. Part of this arose from the B diffusion flux, and part from the chemical effect of the boride layer.

Boride-Enhanced Diffusion in Silicon - Bulk and Surface Layers. N.E.B.Cowern, M.J.J.Theunissen, F.Roozeboom, J.G.M.Van Berkum: Applied Physics Letters, 1999, 75[2], 181-3