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Abstract
The effect of top electrode postanneal on ferroelectric properties of Pt/SrBi2Ta2O9 (SBT)/Pt capacitors is studied. Pt top electrodes on metalorganic derived SBT films were deposited by sputtering with a shadow mask. Well-saturated hysteresis loops of Pt/SBT/Pt capacitors could be achieved after 750 °C postanneal, while the as deposited capacitors exhibit large leakage current. This is ascribed to morphology change of the Pt/SBT interface during postanneal. Interfacial diffusion increases with increasing postanneal time. XPS quantitative analysis shows that 7% of atoms in 50nm-thick Pt top electrodes are Bi atoms after postanneal at 750 °C for 600 s. Remanent polarization decreases with postanneal time from 11.3 μC/cm2 to 7.5 μC/cm2, accompanied with the increase of apparent coercive voltage. The voltage drop across the interfacial layer is found to increase from 0.21 V to 0.36 V.