Defect evolution of low energy, amorphizing germanium implants in silicon

Abstract

The defect evolution upon annealing of low energy, amorphizing germanium implants into silicon was studied using plan-view transmission electron microscopy. Implants with energies of 5–30 keV at an amorphizing dose of 1×1015 Ge+ cm−2 were annealed at 750 °C from 10 s to 360 min. For the implant energies of 10 and 30 keV, the defects form clusters which evolve to {311} defects that subsequently dissolve or form stable dislocation loops. However, as implant energy drops to 5 keV, the interstitials evolve from clusters to small, unstable loops which dissolve within a small time window and do not form {311}’s. To determine the effect of the free surface as an interstitial recombination sink for 5 keV implants, the amorphous layer of a 10 keV implant was lapped to less than the thickness of a 5 keV amorphous layer and then annealed. We found that the defect dissolution observed for the 5 keV implant energy was dependent on the implant energy and not the proximity of the end-of-range damage to the surface. The activation energy of the observed rapid defect dissolution at 5 keV was calculated to be 1.0±0.1 eV.