A semiconductor device including a switching element on a substrate, a pad isolation layer on the switching element, a conductive pad passing through the pad isolation layer and connected to the switching element, an insulating pattern on the pad isolation layer and having a height greater than a horizontal width, a lower electrode on side surfaces of the insulating pattern on side surfaces of the insulating pattern and in contact with the conductive pad, a capacitor dielectric layer on the lower electrode and having a monocrystalline dielectric layer and a polycrystalline dielectric layer, the monocrystalline dielectric layer being relatively close to side surfaces of the insulating pattern compared to the polycrystalline dielectric layer an upper electrode on the capacitor dielectric layer may be provided.