CONTRIBUTION OF ELECTRODES AND MICROSTRUCTURES TO THE ELECTRICAL-PROPERTIES OF PB(ZR0.53TI0.47)O-3 THIN-FILM CAPACITORS

Pb(Zr0.53Ti0.47)O-3 (PZT) thin film capacitors have been fabricated wi th four electrode combinations: Pt/PZT/Pt/SiO2/Si, RuO2/PZT/Pt/SiO2/Si , RuO2/PZT/RuO2/SiO2/Si, and Pt/PZT/RuO2/SiO2/Si. It is shown that pol arization fatigue is determined largely by the electrode type (Pt vs R uO2), and microstructure has only a second-order effect on fatigue. If either the top or bottom electrode is platinum, significant polarizat ion fatigue occurs. Fatigue-free capacitors are obtained only when bot h electrodes are RuO2. In contrast, the bottom electrode is found to h ave a major effect on the leakage characteristics of the PZT capacitor s, presumably via microstructural modifications. Capacitors with botto m RuO2 electrodes show high leakage currents (J = 10(-3)-10(-5) A/cm(2 ) at 1 V) irrespective of the top electrode material. Capacitors with Pt bottom electrodes have much lower leakage currents (J = 10(-8) A/cm (2) at 1 V) irrespective of the top electrode material. At low voltage , the I-V curves show ohmic behavior and negligible polarity dependenc e for all capacitor types. At higher voltages, the leakage current is probably Schottky emission controlled for the capacitors with Pt botto m electrodes.