Compound electrode stack capacitor

This invention is directed to a semiconductor memory device including a storage element comprising a ferroelectric material or a capacitor dielectric material between a top (plate) electrode and a bottom (stack) electrode. In particular, the invention pertains to the design and fabrication of the stack electrode, which is described as compound because it is comprised of two or more materials which are either patterned separately (with at least one material being deposited and patterned prior to the deposition of the others), or arranged so that each of the component materials significantly contributes to the area over which the ferroelectric or capacitor dielectric is initially deposited. These compound stack electrodes may offer ease in processing, more economical use of noble metal materials, and potentially increased mechanical stability (e.g., resistance to hillocking) relative to solid, single-material electrodes of the same dimensions.