High resolution electron microscopy has been used to study the microstructural changes brought about by phoshorus gettering and intrinsic gettering of Ni in Si. Phosphorus gettering proceeds by the formation of SiP particles at the Si/phosphosilicate glass interface, which emit a large concentration of Si interstitials and result in the gettering of Ni to produce NiSi2 particles at the interface. Intrinsic gettering, under the conditions studied, also proceeds by the emission of Si interstitials due to oxygen precipitiation, with no dislocation generation, and results in the production of NiSi2 at the Si/SiO2 interface. It is suggested that the supersaturation of Si interstitials may be responsible for gettering in both cases.