A method for forming a metal-insulator-metal (MIM) capacitor structure is provided. The method includes providing a substrate and forming an interconnect structure over the substrate. The interconnect structure includes a top metal layer, and wherein the top metal layer includes a first portion and a second portion. The method includes forming an insulating layer on the first portion of the top metal layer; and forming a metal pad on the insulating layer. The metal pad includes a first portion and a second portion, the MIM capacitor is constructed by the first portion of the top metal layer, the insulating layer and the first portion of the metal pad, and the second portion of the metal pad directly contacts the first portion of the metal pad and the second portion of the top metal layer.