A semiconductor structure is provided. The semiconductor structure includes a shallow trench isolation (STI) region on a well region of a substrate, a plurality of transistors, and a power rail. Each of the transistors includes at least one fin, a gate electrode formed on the fin, and a doping region formed on the fin. The fin is formed on the well region, and is extending in a first direction. The gate electrode is extending in a second direction that is perpendicular to the first direction. The power rail is formed in the STI region and below the doping regions of the transistors, and extending in the first direction. Each of the doping regions is electrically connected to the power rail, so as to form a source region of the respective transistor. The power rail is electrically connected to the well region of the substrate.