Temperature dependent integrity of Sr_0.8Bi₂Ta₂O₉ films on ultra-thin Al₂O₃ buffered Si

The annealing temperature dependent integrity of Sr_0.8Bi₂Ta₂O₉ (SBT) on ultra-thin 4 nm SiO₂ and Al₂O₃ buffered Si was investigated in this work. Although the capacitance-voltage characteristics show hysteresis loops in both cases, the memory window of Sr_0.8Bi₂Ta₂O₉/Al₂O₃ capacitor is larger than that of Sr_0.8Bi₂Ta₂O₉/SiO₂ capacitor. As increasing annealing temperature from 800 to 900°C, the grain size and memory window of polycrystalline SBT increase both cases. At 800°C, the leakage current density of Sr_0.8Bi₂Ta₂O₉/Al₂O₃ capacitor is 3.2×10^-8 A/cm² at -3 V, which is low enough for deep sub-μm application. With increasing temperature to 900°C, the leakage current in both structures becomes smaller.