Transistor gate structures and methods of forming thereof

Abstract

A device includes a semiconductor substrate; a vertically stacked set of nanostructures over the semiconductor substrate; a first source/drain region; and a second source/drain region, wherein the vertically stacked set of nanostructures extends between the first source/drain region and the second source/drain region along a first cross-section. The device further includes a gate structure encasing the vertically stacked set of nanostructures along a second cross-section. The second cross-section is along a longitudinal axis of the gate structure. The gate structure comprises: a gate dielectric encasing each of the vertically stacked set of nanostructures; a first metal carbide layer over the gate dielectric; and a gate fill material over the first metal carbide layer. The first metal carbide layer comprises Ce, Hf, V, Nb, Sc, Y, or Mo.