A study was made of the B doping of polycrystalline-Si/SiO2/Si structures. The thin oxide layer acted as a stopper to polycrystalline Si removal after doping. When B implantation was used for polycrystalline Si doping, shallow B-doped layers which were suitable for base application could be formed by wet O2 ambient drive-in. When BF2 implantation was used, shallow B-doped layers could be formed even by N2 ambient drive-in. The surface B concentration of B-doped layers increased with the dose and saturated. The B concentration in polycrystalline Si in the region near to the interface with the oxide also increased with dose and saturated. An estimate of the B diffusion coefficient in the oxide showed that it increased by an order of magnitude for B implantation with subsequent wet O2 ambient drive-in and for BF2 implantation with subsequent N2 ambient drive-in.

M.Miyake: Journal of the Electrochemical Society, 1994, 141[6], 1702-8