Performance and variability in multi-VT FinFETs using fin doping

The impact of fin doping (B, P, As) on FinFET device parameters is studied for high-K/midgap metal gate SOI FinFETs. For a fin width of ~25 nm, >;1 V VT modulation is demonstrated from accumulation mode (AM) to inversion mode (IM). IM FinFETs improve short channel FinFET electrostatics, on-off ratio, and VT variability compared to their undoped counterparts. The same parameters degrade in accumulation mode FinFETs. A VT modulation of ±0.25 V using fin B and P doping comes at the expense of 24% and 14% high field mobility penalty for NFET and PFET, respectively. For the same dose, Arsenic is found to modulate the VT more effectively than does Phosphorus. Basic modeling results show that for aggressively scaled (5 nm-wide) fins, the impact of single dopant atom on VT can be as high as 25 mV, severely challenging the viability of the technique towards the end of roadmap.