Gate leakage in hafnium oxide high-k metal gate nMOSFETs

A quasi 1-D quantum mechanical compact model for the gate tunneling current of the metal gate(TiN)/high-k(HfO2)/SiO2/p-Si nMOS capacitor is presented. With this model, measured gate leakage data is investigated using direct tunneling, multiphonon inelastic tunneling, and the Poole-Frenkel conduction mechanism. The thicker devices present a Poole-Frenkel like behaviour. The relative contributions of direct tunneling and the Poole-Frenkel like conduction to the gate leakage for intermediate thickness devices remain unresolved, while the thinner devices exhibit direct tunneling and inelastic tunneling as the dominant mechanisms.