US Patent 11495661 Semiconductor device including gate barrier layer

A semiconductor device including a barrier layer surrounding a work function metal layer and methods of forming the same are disclosed. In an embodiment, a semiconductor device includes a semiconductor substrate; a first channel region over the semiconductor substrate; a second channel region over the first channel region; gate dielectric layers surrounding the first channel region and the second channel region; work function metal layers surrounding the gate dielectric layers; and barrier layers surrounding the work function metal layers, a first barrier layer surrounding the first channel region being merged with a second barrier layer surrounding the second channel region.