Semiconductor device and method of forming thereof

Abstract

A method includes forming a semiconductor region, forming a gate spacer over the semiconductor region, forming a source / drain region aside of the semiconductor region, wherein the source / drain region is of p-type, and forming a gate dielectric over the semiconductor region. The gate dielectric is formed in a space between opposing portions of the gate spacer. A ruthenium oxide layer is formed over the gate dielectric, and acts as a part of a work-function layer of a gate electrode. The method further includes incorporating silicon into the ruthenium oxide layer.