Room-temperature migration and interaction of ion beam generated defects in crystalline silicon

We have investigated the room-temperature migration properties of ion generated defects in crystalline Si. The defects were injected into the bulk of a pure epitaxial Si layer bf a low energy (40 keV) Si implant and monitored using a preexisting defect distribution, produced by a high energy He implant, as a marker. The depth of this defective marker layer was changed by varying in the range 1-3 MeV. Spreading resistance measurements show that the injected defects produce a partial annihilation of the pre-existing damage. The magnitude of the annihilation process is strongly dependent on the depth of the defective marker, being very large when this marker is confined within 5 mu m from the surface and negligible when it lies beyond a depth of similar to 10 mu m. From these results, detailed information on the nature of ion-generated defects which are injected and on their migration properties is obtained. It is found that the observed phenomena are clue to the annihilation of divacancies and phosphorus-vacancy defect complexes, generated by the He implant, by Si self-interstitials injected by the shallow Si implant.