Phase evolution and annealing effects on the electrical properties of Pb(Zr 0.53Ti 0.47)O 3 thin films with RuO 2 electrodes

Abstract

The electrical properties and crystallization of Pb(Zr 0.53Ti 0.47)O 3 (PZT) thin films grown on RuO 2 electrodes by the sol-gel process have been studied. It was found that the amorphous as-deposited thin film first transforms to a pyrochlore phase at 500 °C. On further annealing, perovskite PZT begins to crystallize at about 600 °C. TEM anlysis reveals that a pyrochlore-type second phase still exists in the films even after annealing to temperatures of 750 °C for 10 min. These PZT films are fatigue-free, but they show large property variation and high leakage currents ( J = 10 −3Acm −2 at 1 V). An 800 °C annealing treatment, for 10 min in air of the RuO 2 bottom electrode prior to film deposition enhanced perovskite PZT nucleation, thereby eliminating the pyrochlore-type second phase. In addition, the leakage currents of PZT films grown on annealed RuO 2 electrodes are about two orders of magnitude lower than those of PZT films grown on unannealed RuO 2. It is also observed that annealing the entire capacitor stack after the top electrode deposition improved capacitor properties.