A semiconductor device includes a first power rail, a second power rail, at least one standard cell and at least one power bridge. The first power rail extends in a first direction over a substrate. The second power rail extends in the first direction over the substrate, and the second power rail is spaced apart from the first power rail in a second direction that intersects the first direction. The at least one standard cell receives a first voltage from the first and the second power rails. The at least one power bridge connects the first power rail and the second power rail in the second direction. The first power rail and the second power rail are formed in a first metal layer and the least one power bridge is formed in a bottom metal layer that is under the first metal layer.