A novel Ir/IrO/sub 2//Pt-PZT-Pt/IrO/sub 2//Ir capacitor for a highly reliable mega-scale FRAM

A novel Ir/IrO/sub 2//Pt-PZT-Pt/IrO/sub 2//Ir capacitor is proposed for a highly reliable mega-scale FRAM. It was observed that charge degradation in retention test depends on the condition of the interface between top electrode and PZT thin film in ferroelectric capacitor. Nonvolatile polarization value of the novel capacitor after the retention acceleration is 4.7 times larger than that of Ir/IrO/sub 2/-PZT-Pt/IrO/sub 2//Ir capacitor. The novel Pt-inserted capacitor shows a great endurance up to 10/sup 11/ fatigue cycles. The 4 Mb FRAM device with Ir/IrO/sub 2//Pt-PZT-Pt/IrO/sub 2//Ir capacitor has a wide sensing window of 90 fC even after baking at 125/spl deg/C for 88 hours.