Metal gate VT modulation using PLAD N2 implants for Ge p-FinFET applications

This work reports multi-V_T Ge gate stacks using low energy plasma-assisted doping (PLAD) with N₂ for Ge p-FinFET applications. Varying implant dose and energy is used to demonstrate effective TiN work-function tuning over a range of 170 mV from near-midgap to near-valence band edge of Ge without significant impact on gate capacitance (effective oxide thickness (EOT)), interface quality and TiN resistance. However, unlike Si gate stacks, increased gate leakage in implanted samples is likely due to traps created in the HfO₂ Hi-k layer and exposed to channel carriers due to a low band offset GeO₂ interfacial layer.