Abstract
The concentration of vacancy-type defects in a silicon-on-insulator substrate consisting of a 110 nm overlayer and a 200 nm buried oxide has been quantified using variable energy positron annihilation spectroscopy following 300 keV Si+ ion implantation to a dose of 1.5 x 10(15) cm(-2) and subsequent, annealing at temperatures ranging from 300 to 700 degrees C. The preferential creation of vacancies (relative to interstitials) in the silicon overlayer leads to a net vacancy-type defect concentration after annealing. Assuming that the defects have a structure close to that. of the divacancy we determine the concentration to range from 1.7 x 10(19) to 5 x 10(18) cm(-3) for annealing temperatures ranging from 300 to 700 degrees C. The measured defect concentration is in excellent agreement with that predicted via Monte Carlo simulation. The impact of this net vacancy population on the diffusion and activation of phosphorus introduced by a 2 keV implantation to a dose of 1 x 10(15) cm(-2) has been observed. For samples that combine both Si+ and P+ implantations, postimplantation phosphorus diffusion is markedly decreased relative to that for P+ implantation only. Further, a fourfold increase in the electrical activation of phosphorus after postimplantation annealing at 750 degrees C is observed when both implantations of Si+ and P+ are performed. We ascribe this affect to the reduction in phosphorus-interstitial clusters by the excess vacancy concentration beyond the amorphous/crystalline interface created by the P+ implantation. (C) 2009 American Institute of Physics. [doi:10.1063/1.3262527]