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 V_T modulation is demonstrated from accumulation mode (AM) to inversion mode (IM). IM FinFETs improve short channel FinFET electrostatics, on-off ratio, and V_T variability compared to their undoped counterparts. The same parameters degrade in accumulation mode FinFETs. A V_T 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 V_T more effectively than does Phosphorus. Basic modeling results show that for aggressively scaled (5 nm-wide) fins, the impact of single dopant atom on V_T can be as high as 25 mV, severely challenging the viability of the technique towards the end of roadmap.