A semiconductor device including a gate structure present on a channel portion of a semiconductor substrate and at least one gate sidewall spacer adjacent to the gate structure. In one embodiment, the gate structure includes a work function metal layer present on a gate dielectric layer, a metal semiconductor alloy layer present on a work function metal layer, and a dielectric capping layer present on the metal semiconductor alloy layer. The at least one gate sidewall spacer and the dielectric capping layer may encapsulate the metal semiconductor alloy layer within the gate structure.