Implantation and transient B diffusion in Si: The source of the interstitials

Abstract

Implanted B and P dopants in Si exhibit transient enhanced diffusion (TED) during initial annealing, due to Si interstitials being emitted from the region of the implant damage. The structural source of these interstitials has not previously been identified. Quantitative transmission electron microscopy measurements of extended defects are used to demonstrate that TED is caused by the emission of interstitials from specific defects. The defects are rodlike defects running along 〈110〉 directions, which consist of interstitials precipitating on {311} planes as a single monolayer of hexagonal Si. We correlate the evaporation of {311} defects during annealing at 670 and 815 °C with the length of the diffusion transient, and demonstrate a link between the number of interstitials emitted by the defects, and the flux of interstitials driving TED. Thus not only are {311} defects contributing to the interstitial flux, but the contribution attributable to {311} defect evaporation is sufficient to explain the whole of the observed transient. The {311} defects are the source of the interstitials.