Contribution of electrodes and microstructures to the electrical properties of Pb(Zro.53Tio.47)03 thin film capacitors

Pb(Zr0.53Tio.47)C>3 (PZT) thin film capacitors have been fabricated with four electrode combinations: Pt/PZT/Pt/Si02/Si, RuO2/PZT/Pt/Si02/Si, Ru02/PZT/Ru02/Si02/Si, and Pt/PZT/Ru02/Si02/Si. It is shown that polarization fatigue is determined largely by the electrode type (Pt vs Ru02), and microstructure has only a second-order effect on fatigue. If either the top or bottom electrode is platinum, significant polarization fatigue occurs. Fatigue-free capacitors are obtained only when both electrodes are Ru02. In contrast, the bottom electrode is found to have a major effect on the leakage characteristics of the PZT capacitors, presumably via microstructural modifications. Capacitors with bottom Ru02 electrodes show high leakage currents (J = 10”3“1CT5 A/cm2 at 1 V) irrespective of the top electrode material. Capacitors with Pt bottom electrodes have much lower leakage currents (J = 10–8A/cm2 at 1 V) irrespective of the top electrode material. At low voltage, the I-V curves show ohmic behavior and negligible polarity dependence for all capacitor types. At higher voltages, the leakage current is probably Schottky emission controlled for the capacitors with Pt bottom electrodes.