A SrRuO₃/IrO₂ top electrode FeRAM with Cu BEOL process for embedded memory of 130 nm generation and beyond

A damage-robust SrRuO₃/IrO₂ top electrode FeRAM with Cu BEOL process is demonstrated for the first time as a promising device for 130 nm CMOS embedded non-volatile memory. The ferroelectric capacitor with SrRuO₃/IrO₂ top electrode has no degradation during Cu metallization to suppress oxygen and lead vacancies at a top electrode interface. Switching charge (Q_sw) of 40 μC/cm² is achieved for 0.45 × 0.45 μm² top electrode (TE) size capacitor. Ninety percent saturation of Q_sw is obtained at 1.1 V that is low enough to drive ferroelectric capacitors at 1.8 V for 130 nm CMOS. Opposite state polarization margin more than 90% is retained against imprint after the high temperature storage at 150 °C for 70 h. The combination of this high reliable capacitor with large Q_sw and Chain FeRAM™ architecture with a small bit line capacitance [Ozaki T, Iba J, Yamada Y, Kanaya H, Morimoto T, Hidaka O, et al. In: Symposium on VLSI technologies technical digest; 2001. p. 113] drastically increases signal window for 1T1 C operation. A sharp signal distribution and a large peak-to-peak signal window of 730 mV at 1.8 V on the test device with 0.20 μm² area capacitors using three-level Cu metallization on 32 Mb Chain FeRAM™ are obtained. This technology realizes reliable embedded FeRAM of 130 nm generation and beyond.