Integrated Ferroelectrics

Fabrication of multilayer ferroelectric films

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Multilayers of strontium bismuth tantalate (Sr0.9Bi2.2Ta2O9, SET) with bismuth titanate (Bi4Ti3O12, BT), and SBT and strontium bismuth niobate (Sr0.9Bi2.2Nb2O9, SEN) with BT were prepared by chemical solution deposition (CSD). The CSD solutions were a mixture of strontium, tantalum, niobium and titanium butoxyethoxides and bismuth ethylhexanoate dissolved in butoxyethanol. SBT films were fabricated and annealed at 800 °C for 60 min. Generally, all capacitors of the SBT films tested had low resistance with as-deposited Pt top electrodes and no ferroelectricity could be measured. After a post electrode anneal at 800 °C for 30 min, a percentage of capacitors could be tested for ferroelectricity, and a 2Pr of 15 μC/cm2 at 3V was typically measured. Multilayer SBT, and SBT and SEN with BT were rapidly thermally annealed for a total (including post electrode anneal) of 20-40 min at 750 °C. The multilayer SBT and SEN with BT, and SBT with BT films exhibited a wide range of 2Pr values ranging from 2-14 μC/cm2 at 3V but had a larger percentage of measurable capacitors after post electrode anneal than the SBT only films. In addition, no fatigue was observed after 1011 cycles in a SBT with BT multilayer structure. © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint.