Provided are semiconductor devices and methods of fabricating the same. The device may include a substrate including a first surface and a second surface opposing each other, a through-silicon-via (TSV) electrode provided in a via hole that may be formed to penetrate the substrate, and an integrated circuit provided adjacent to the through electrode on the first surface. The through electrode includes a metal layer filling a portion of the via hole and an alloy layer filling a remaining portion of the via hole. The alloy layer contains at least two metallic elements, one of which may be the same as that contained in the metal layer, and the other of which may be different from that contained in the metal layer.