Disclosed is a semiconductor device including a conductive pattern on a substrate, a passivation layer on the substrate and including an opening that partially exposes the conductive pattern, and a pad structure in the opening of the passivation layer and connected to the conductive pattern. The pad structure includes a first metal layer that fills the opening of the passivation layer and has a width greater than that of the opening, and a second metal layer on the first metal layer. The first metal layer has a first thickness at an outer wall of the first metal layer, a second thickness on a top surface of the passivation layer, and a third thickness on a top surface of the conductive pattern. The second thickness is greater than the first thickness, and the third thickness is greater than the second thickness.