Room-temperature diffusion and gettering of Au in silicon stimulated by MeV electron irradiation

A novel effect of room-temperature diffusion and gettering of Au from the bulk to the surface defect region of a Si wafer stimulated by 5 MeV electron irradiation is demonstrated. The Au atoms were introduced into the Si wafer by ion implantation. According to the secondary ion mass spectrum and the minority carrier lifetime measurements, it is found that 5 MeV electron irradiation with a small dose: e.g. 50 Gy, could effectively draw Au atoms from the bulk of a Si wafer to the surface defect region at room temperature, which is very different from the traditional gettering processes for transition metal impurities in Si where high temperature is necessary. The experimental evidence indicates that the room temperature gettering of Au in Si stimulated by 5 MeV electron irradiation is stronger than that stimulated by Co-60 gamma ray irradiation in two aspects: with the same irradiation dose of 50 Gy and the same surface defect regions, the Au concentration profile of Au implanted Si samples getterred by 5 MeV electron irradiation shifts closer towards the surface defect region than that getterred by Co-60 gamma ray irradiation; secondly, with the same surface defect region, the increment of the bulk minority carrier lifetime induced by the gettering of Au stimulated by 25 Gy 5 MeV electron irradiation is larger than 70%, however, even under 100 Gy, the lowest gamma ray irradiation dose used, the increment of the bulk minority carrier lifetime induced by the gettering of Au stimulated by Co-60 gamma ray irradiation is less than 5%.SCI(E)EIARTICLEqingg@pku.edu.cn274