Abstract: The present disclosure relates to a method of forming a MIM (metal-insulator-metal) capacitor using a post capacitor bottom metal (CBM) treatment process to reduce a roughness of a top surface of a capacitor bottom metal layer, and an associated apparatus. In some embodiments, the method is performed by forming a capacitor bottom metal layer having a first metal material over a semiconductor substrate. A top surface of the capacitor bottom metal layer is exposed to one or more post CBM treatment agents having oxygen. The one or more post CBM treatment agents reduce a roughness of the top surface and form an interface layer having the first metal material and oxygen onto and in direct contact with the top surface of the capacitor bottom metal layer. A capacitor dielectric layer is formed over the interface layer and a capacitor top metal layer is formed over the capacitor dielectric layer.