This invention provides a semiconductor device that can minimize deterioration of electric characteristics of the semiconductor device while minimizing the amount of etching required. In the semiconductor device of the invention, a pad electrode layer formed of a first barrier layer and an aluminum layer laminated thereon is formed on a top surface of a semiconductor substrate. A supporting substrate is further attached on the top surface of the semiconductor substrate. A second barrier layer is formed on a back surface of the semiconductor substrate and in a via hole formed from the back surface of the semiconductor substrate to the first barrier layer. Furthermore, a wiring layer is formed in the via hole so as to completely fill the via hole or so as not to completely fill the via hole. A ball-shaped terminal is formed on the wiring layer.