A semiconductor device is disclosed. The semiconductor device includes a substrate and capacitor electrically connected to the substrate. The capacitor includes a lower electrode, a dielectric layer disposed on the lower electrode, and an upper electrode disposed on the dielectric layer. The upper electrode includes a first electrode on the dielectric layer and a second electrode on the first electrode, such that the first electrode is disposed between the dielectric layer and the second electrode. The first electrode contains metal oxynitride having a formula of MxOyNz, in which an atomic ratio (y/x) of oxygen (O) to metallic element (M) is a value in the range from 0.5 to 2.