Effective Work Function of Scandium Nitride Gate Electrodes on SiO2 and HfO2

For n -type metal–oxide–semiconductor (NMOS) devices, a metal gate with a very low effective work function (Φ m,eff ) is necessary. In this paper, we evaluate the Φ m,eff values of ScN x gates on both SiO 2 and atomic-layer-deposited (ALD) HfO 2 . The ScN x /SiO 2 samples have a wide range of Φ m,eff values from ∼3.9 to ∼4.7 eV. However, the ScN x gates on HfO 2 show a relatively narrow range of Φ m,eff values from ∼4.5 to ∼4.8 eV due to the Fermi level pinning (FLP) effect. The generation of oxygen vacancies may result in the extrinsic FLP near the ScN x /HfO 2 interface. Therefore, ScN x is an NMOS-compatible electrode on SiO 2 and the extrinsic FLP should be suppressed for NMOS devices with HfO 2 .