The present disclosure relates to a semiconductor device and a manufacturing method, and more particularly to a 3D metal insulator metal (MIM) capacitor structure with an increased capacitance per unit area in a semiconductor structure. The MIM structure includes a substrate, an oxide layer formed over the substrate, and a first metal layer formed over the oxide layer. The first metal layer includes a plurality of mandrels formed on a surface of the first metal layer. The MIM structure also includes a dielectric layer formed over the first metal layer and the plurality of mandrels, a second metal layer formed over on the dielectric layer, and one or more interconnect structures electrically connected to the first and second metal layers.