Independent interface and bulk film contributions to reduction of tunneling currents in stacked oxide/nitride gate dielectrics with monolayer nitrided interfaces

Abstract

Direct tunneling limits aggressive scaling of thermally-grown oxides to about ∼1.6 nm, a thickness at which the tunneling current at 1 V is ∼1 A/cm 2. This paper presents experimental results, supported by interface characterizations and model calculations, which demonstrate that multi-layer or stacked gate dielectrics prepared by remote plasma processing comprised of (i) ultra-thin nitrided SiO 2 interface layers, and (ii) either silicon nitride or oxynitride bulk dielectric films, can extend the oxide-equivalent thickness, t ox-eq, limit down to ∼1.1–1.0 nm. A similar stacked gate dielectric, which substitutes higher- k oxides such as Zr(Hf)O 2–SiO 2 ‘silicate’ alloys or Ta 2O 5 for the nitrides or oxynitride alloys, is projected to further reduce t ox-eq to ∼0.6–0.7 nm.