Controlling crystallization of Pb(Zr,Ti)O3 thin films on IrO2 electrodes at low temperature through interface engineering

Abstract

Pb ( Zr,Ti ) O 3 (PZT) capacitors were fabricated on IrO2–Si substrates with and without SrRuO3 (SRO) template layers using a modified sol-gel process. The crystallization temperature of PZT films was lowered significantly by interposing a thin SRO layer between the PZT and IrO2, which modifies the nucleation and growth of perovskite PZT by acting as a structural and chemical template. At 450 °C, the films deposited directly on IrO2 were not perovskite phase and therefore not ferroelectric; at 550 °C, they exhibited a mixed perovskite–pyrochlore microstructure. In contrast, the introduction of a thin (10–50 nm) SRO template layer yielded complete perovskite phase at temperatures down to 450 °C. Test capacitors exhibited desirable ferroelectric properties, including low saturation voltage, high resistivity, small pulse-width dependence, and good fatigue endurance, which provides a promising way to low-temperature integration of high-density ferroelectric random access memories with a stacked-type capacitor structure.