The effects of the catalytic nature of capacitor electrodes on the degradation of ferroelectric Pb(Zr,Ti)O3 thin films during reductive ambient annealing

The disappearance of ferroelectricity in Pb(Zr0.52,Ti0.48)O3 (PZT) thin-film capacitors, which is caused by heat treatment in a reductive ambience, is investigated. Bare PZT films are not damaged by annealing in a hydrogen-containing atmosphere (H2 annealing) up to 400 °C, whereas a PZT capacitor with Pt electrodes loses its ferroelectricity during annealing at less than 300 °C. We have found that the degradation of ferroelectricity depends upon the metal used for the top electrode of the PZT capacitor. The increased degradation in the case of a PZT capacitor with Pt electrodes can be explained by a catalytic reaction on the Pt surface. We have made the ferroelectricity of a Pt/PZT/Pt capacitor retained even after the H2 annealing at 300 °C, or above, simply by oxidizing it before the H2 annealing.