Modeling C-V shifts in boron/BF/sub 2/-implanted capacitors

We report on fabricated capacitors following B and BF/sub 2/ implantation with near-identical boron profiles as measured by SIMS. The C-V curves showed flatband shifts between the two implanted species which increase with the implant dose, up to 0.27 V for 1e14 cm/sup -2/. Modeling the processing with an interface trap model for boron in the case of BF/sub 2/ implant but not for B, gave good agreement with both SIMS doping profiles and the C-V curves, and reproduced the C-V shifts. This effect is predicted to have a significant impact on MOS V/sub th/.