The B was implanted into crystalline Si, through oxide layers with various thicknesses, using various doses and energies. Rapid thermal annealing was used to obtain shallow junctions and electrical activation of the B atoms. However, a transient enhanced diffusion which was induced by implantation damage was observed. The B concentration profiles before and after annealing were obtained by means of secondary ion mass spectrometry. It was found that the diffusion transient in the tail region of the B profile increased with decreasing oxide thickness. When the concentration peak was located in this oxide, the O which was knocked into the Si substrate could play an important role in restricting B diffusion. In thinner oxides, the B enhanced diffusion was attributed to implantation-induced damage in the Si at high doses. The diffusion process of B in oxide and monocrystalline Si during rapid thermal annealing was investigated. The B diffusion profiles which were obtained by computer simulation were compared with experimental data. This showed that the intrinsic coefficient could not be considered to be constant throughout the depth of the Si.

L.Kaabi, C.Gontrand, M.Lemiti, B.Balland: Physica Status Solidi A, 1993, 138[1], 99-109