Low work-function TaN-metal gate with Gadolinium oxide buffer layer on Hf-based dielectrics

Abstract

Reduction in effective work function (EWF) of mid gap-TaN metal gate electrode with Gadolinium (Gd2O3) buffer layer in Hafnium based high-K gate stack has been demonstrated. EWF of 4.2eV was achieved for TaN with a bi-layer arrangement of Gd2O3/HfSiOx dielectric. By using Gd-Si co-sputtered layer on HfO2, a reduction in EWF to NMOS compatible EWF of 4.05eV was obtained. NMOSFETs with improved output current, transconductance, and channel electron mobility highlight the approach of using Gadolinium in the gate stack.