Atomistic study of metal/high-K interface

Abstract

This paper describes our ab initio method to evaluate the effective work function of a MOS metal gate on HfO2 oxide which is different from the vacuum one because of the Fermi pinning. The computation relies on Density Functional Theory (DFT) and Many Body theory. Firstly a monoclinic cell is computed using DFT to obtain a band structure; this one is corrected using the GW approximation. Then a stack made of W + HfO2 is computed and using Van de Walle and Martins method, the energy bands alignment along the stack is obtained. Finally HfO2 energies in the stack are corrected according to our previous computation on the HfO2 cell. This calculation brings an evaluation of the valence band offset at the W/HfO2 interface and the effective work function of W on HfO2.