Metal insulator metal (MIM) capacitor fabrication with sidewall spacers and aluminum cap (ALCAP) top electrode

A method of forming a MIM (metal insulator metal) capacitor is disclosed whereby adverse affects associated with copper diffusion are mitigated even as the capacitor is scaled down. A sidewall spacer is formed against an edge of a layer of bottom electrode/copper diffusion barrier material, an edge of a layer of capacitor dielectric material and at least some of an edge of a layer of top electrode material. The sidewall spacer is dielectric or non-conductive and mitigates "shorting" currents that can develop between the plates as a result of copper diffusion. Bottom electrode diffusion barrier material mitigates copper diffusion and/or copper drift, thereby reducing the likelihood of premature device failure.