Metal-insulator-metal capacitor and method for forming same

The invention provides a metal-insulator-metal (MIM) capacitor and a method for forming the same. The method comprises steps of: providing a substrate, wherein a first conductive layer, a first insulated layer, and a second conductive layer are disposed on the substrate from top to bottom; etching the first conductive layer to form a first electrode which exposes a part of the first insulated layer; forming a second insulated layer covering the top surface and the sidewall of the first electrode and a part of the top surface of the first insulated layer; etching the second insulated layer and the first insulated layer until the second conductive layer is exposed, a sidewall structure is formed by the second insulated layer remaining at the surface of the sidewall of the first electrode and the first insulated layer under the second insulated layer, and a dielectric layer is formed by the first insulated layer under the first electrode; and etching the second conductive layer to form a second electrode. The method for forming the MIM capacitor may decrease etching damage to the dielectric layer in the MIM capacitor.