NMOS Compatible Work Function of TaN Metal Gate With Erbium-Oxide-Doped Hafnium Oxide Gate Dielectric

This letter demonstrates reduction in effective work function of tantalum-nitride (TaN) metal gate with erbium-oxide-doped hafnium oxide. We report that TaN effective metal-gate work function can be tuned from Si midgap to the conduction band to meet the work-function requirement of NMOSFETs by incorporating ErO in HfO2with an equivalent oxide thickness as low as 1.15 nm. Several other lanthanide-oxide doped hafnium oxides show similar characteristics.