Donor activation and damage in Si–SiO2 from low-dose, low-energy ion implantation studied via electrical transport in MOSFETs

Using silicon MOSFETs with thin (5 nm) thermally grown SiO2 gate dielectrics, we characterize the density of electrically active traps at low temperature after 16 keV phosphorus ion implantation through the oxide. We find that, after rapid thermal annealing at 1000 ◦C for 5 s, each implanted P ion contributes an additional 0.08 ± 0.03 electrically active traps, whilst no increase in the number of traps is seen for comparable silicon implants. This result shows that the additional traps are ionized P donors, and not damage due to the implantation process. We also find, using the room temperature threshold voltage shift, that the electrical activation of donors at an implant density of 2 × 1012 cm−2 is ∼100%. (Some figures in this article are in colour only in the electronic version)