A semiconductor structure includes an interposer substrate having an upper surface, a lower surface opposite to the upper surface, and a device region. A first redistribution layer is formed on the upper surface of the interposer substrate. A guard ring is formed in the interposer substrate and surrounds the device region. At least a through-silicon via (TSV) is formed in the interposer substrate. An end of the guard ring and an end of the TSV that are near the upper surface of the interposer substrate are flush with each other, and are electrically connected to the first redistribution layer.