A method of etching a ferroelectric capacitor stack structure including conductive upper and lower plates with a ferroelectric material, such as lead-zirconium-titanate (PZT), therebetween, with each of these layers defined by the same hard mask element. The stack etch process involves a plasma etch with a fluorine-bearing species as an active species in the etch of the conductive plates, and a non-fluorine-bearing chemistry for etching the PZT ferroelectric material. An example of the fluorine-bearing species is CF4. Endpoint detection can be used to detect the point at which the upper plate etch reaches the PZT, at which point the gases in the chamber are purged to avoid etching the PZT material with fluorine. A steeper sidewall angle for the capacitor structure can be obtained.