Semiconductor device and manufacturing method thereof

Abstract

A semiconductor device includes a semiconductor substrate, a first gate structure over the substrate, a second gate structure over the substrate, first gate spacers, second gate spacers, first and second metal layers spanning over the first and second gate structures, first and second contact plugs extending through the first and second metal layers, respectively. The first gate structure includes a first gate dielectric, and a first work function metal layer over the first gate dielectric. The second gate structure is wider than the first gate structure, wherein the second gate structure includes a second gate dielectric, a second work function metal layer over the second gate dielectric, and a filling conductor over the second work function metal layer. The first contact plug is in contact with the first work function metal layer, and the second contact plug is in contact with the filling conductor.