We have analyzed the perturbations produced by recombination at surface, trapping at impurities, and stress fields on the room-temperature migration properties of point defects in Si. A stack consisting of a Si oxide (or a Si nitride) and a polycrystalline Si layer, deposited on Si samples, was patterned to open 2-μm-wide, 10-μm-spaced stripes. A 40-keV Si implantation to fluences of 1×1012–5×1013/cm3, performed through this mask at room temperature, was used to inject point defects into the bulk of the wafer. After implants, defect-induced dopant deactivation, in the cross section orthogonal to the direction of the stripes, has been monitored using two-dimensional spreading resistance profilometry. It has been found that, in highly pure epitaxial Si samples, dopant deactivation extends in depth to several microns beyond the region (∼0.4 μm) directly modified by the ions. Furthermore, the two-dimensional deactivation profiles exhibit a strong recess at the surface and a significant anisotropy, being markedly elongated in the lateral direction. Analysis of the data shows that long-range migration of defects is interrupted by trapping at impurities (C and O) or recombination at the surface, characterized by a coefficient of ∼100 μm-1. Moreover, the lateral elongation of the profiles is tentatively explained assuming an anisotropy in the defect diffusivity tensor produced by the strain field under the mask. © 1998 American Institute of Physics.