C. S. Park, G. Bersuker, S. C. Song, P. Kirsch & B. H. Lee, SEMATECH, Austin, Texas; R. Jammy, IBM assignee to SEMATECH

ABSTRACT

This paper describes recent progress in high-k/metal gate stacks required for MOSFET scaling to the 32nm technology node. Band-edge metals for n- and p-MOSFETs have been developed through effective work function (WF) tuning, achieved by optimized doping of the high-k gate stacks. The mechanism of the EWF tuning is the dipole formation at the interface of the high-k dielectric and SiO₂ interfacial layer. Possible solutions to the flatband voltage (V_fb) roll-off issue were obtained, an issue that presents the most significant challenge to achieving low pMOSFET threshold voltage (|V_t|) at low EOTs. The gate-first high-k/metal gated n- and pMOSFETs with low |V_t| and low EOT suitable for 32nm technology node applications have been successfully demonstrated.