A semiconductor structure including a capacitor having increased capacitance and improved electrical performance is provided. The semiconductor structure includes a substrate and a MIM capacitor over the substrate. The MIM capacitor includes a bottom plate, an insulating layer over the bottom plate, and a top plate over the insulating layer. The semiconductor structure further includes a MOS device including a gate dielectric over the substrate and a metal-containing gate electrode free from polysilicon on the gate dielectric, wherein the metal-containing gate electrode is formed of a same material and has a same thickness as the bottom plate.