US Patent 11444198 Work function control in gate structures

A semiconductor device with different gate structure configurations and a method of fabricating the same are disclosed. The semiconductor device includes a fin structure disposed on a substrate, a nanostructured channel region disposed on the fin structure, and a gate-all-around (GAA) structure surrounding the nanostructured channel region. The GAA structure includes a high-K (HK) gate dielectric layer with a metal doped region having dopants of a first metallic material, a p-type work function metal (pWFM) layer disposed on the HK gate dielectric layer, a bimetallic nitride layer interposed between the HK gate dielectric layer and the pWFM layer, an n-type work function metal (nWFM) layer disposed on the pWFM layer, and a gate metal fill layer disposed on the nWFM layer. The pWFM layer includes a second metallic material and the bimetallic nitride layer includes the first and second metallic materials.