Electrical properties of PZT thin films with Ir and IrO2 electrodes

The development of ferroelectric memory devices requires an understanding of the fatigue properties of ferroelectric thin films. PZT thin films by sol-gel method on Pt/Ti with residual polarization reduced by continuous polarization reversal about 10⁸ cycles. In this paper, we regard Ir, IrO₂ and these layer films as electrode materials and have evaluated the electric characteristic of PZT thin film capacitors. Regarding the ferroelectric material, we used PZT(Zr/Ti=52/48) by sol-gel method. By using Ir and IrO₂ electrodes, the diffusion barrier effect becomes very good, therefore they can prevent Pb and other elements from diffusing into the electrode and polycrystalline silicon (poly-Si). PZT thin films using Ir/IrO₂ layer electrodes show no fatigue up to 10¹² cycles of ±5 V switching pulses