New route to zero-barrier metal source/drain MOSFETs

A new method for dramatically lowering the Schottky barrier resistance at a metal/Si interface by interposing an ultrathin insulator is demonstrated for the first time, with thermionic barriers less than those reported to date with silicides. Results with Er and near-monolayer thermal SiNx at the interface are consistent with simulations of effective metal Fermi level separations from the silicon conduction band of 0.15 V for n-type Si and 45 mV for p-type Si. Simulations of advanced metal source/drain (S/D) ultrathin-body CMOS devices in comparison with competitive doped S/D devices show a significant performance advantage with a barrier to the conduction band of up to 0.1 V.