The present disclosure provides various embodiments of a semiconductor device and method of fabricating the semiconductor device. An exemplary semiconductor device includes a semiconductor substrate and a gate stack disposed over the semiconductor substrate. The gate stack includes a gate dielectric layer disposed over the semiconductor substrate and a tuned, stressed metal gate layer disposed over the gate dielectric layer. The tuned, stressed metal gate layer includes a stress that distributes strain differently to portions of the semiconductor substrate having different surface characteristics. In an example, the gate stack is disposed over a portion of a fin of the semiconductor substrate, and the fin has a varying thickness, providing a fin with a roughened surface. The tuned, stressed metal gate layer includes a stress that distributes strain differently to portions of the fin having different thicknesses.