PZT MIM capacitor with oxygen-doped Ru-electrodes for embedded FeRAM devices

An add-on-type, Pb(Zr,Ti)O₃ (PZT) metal-insulator- (MIM) capacitor on Al multilevel interconnects is developed for embedded FeRAM devices, concluding that the oxygen-doping into the ruthenium (Ru) electrodes is crucial for obtaining large remnant polarization under a limited process temperature below 450°C. The oxygen-doped, Ru bottom-electrode with a granular structure reduces the PZT sputtering temperature below 450°C to obtain the ferroelectric perovskite-phase. On the other hand, oxygen doping into the Ru top-electrode suppresses the reductive damage at the interface between the top-electrode and the PZT, keeping the leakage current low. The PZT MIM capacitor with these oxygen-doped, Ru electrodes exhibits the remnant polarization of 21 μC/cm² on the Al multilevel interconnects with no degradation of the interconnect reliability, thus applicable to the embedded FeRAM in 0.25 μm-CMOS logic LSIs.