Capacitor and methods of manufacturing the same

In a capacitor having a semiconductor-insulator-metal (SIM) structure, an upper electrode may be formed into a multilayer structure including a polycrystalline semiconductor Group IV material. A dielectric layer may include a metal oxide, and a lower electrode may include a metal-based material. Therefore, a capacitor may have a sufficiently small equivalent oxide thickness (EOT) and/or may have improved current leakage characteristics.