Experimental and theoretical investigation of the effect of SiO 2 content in gate dielectrics on work function shift induced by nanoscale capping layers

Abstract

The impact of SiO 2 content in ultrathin gate dielectrics on the magnitude of the effective work function (EWF) shift induced by nanoscale capping layers has been investigated experimentally and theoretically. The magnitude of the effective work function shift for four different capping layers (AlN, Al 2O 3, La 2O 3, and Gd 2O 3) is measured as a function of SiO 2 content in the gate dielectric. A nearly linear increase of this shift with SiO 2 content is observed for all capping layers. The origin of this dependence is explained using density functional theory simulations. © 2012 American Institute of Physics.