A semiconductor device and methods of formation are provided. A semiconductor device includes an annealed cobalt plug over a silicide in a first opening of the semiconductor device, wherein the annealed cobalt plug has a repaired lattice structure. The annealed cobalt plug is formed by annealing a cobalt plug at a first temperature for a first duration, while exposing the cobalt plug to a first gas. The repaired lattice structure of the annealed cobalt plug is more regular or homogenized as compared to a cobalt plug that is not so annealed, such that the annealed cobalt plug has a relatively increased conductivity or reduced resistivity.