Submicron Ferroelectric Capacitors Fabricated by Chemical Mechanical Polishing Process for High-Density Ferroelectric Memories

Submicron ferroelectric capacitors were fabricated by a damascene process using chemical mechanical polishing (CMP). The fabricated capacitors consisted of SrBi2Ta2O9 (SBT) film with top and bottom electrodes of IrO2 films. The capacitor size was 0.8 µm in diameter, that is, 0.5 µm2 in area. Damage by the fabrication process was not observed in electrical measurements, such as the dependence of remanent polarization on electric field and leakage current properties. The remanent polarization (2Pr) of 5 µC/cm2 at the saturation voltage of 2 V is half that of a large capacitor because the SBT films were composed of single-crystal grains in the bismuth-layered perovskite structure and micro-crystals in many phases including pyrochlore. The crystallinity of the SBT films may be associated with the redistribution of Bi between the SBT thin films and the IrO2 electrodes during the crystallization annealing of SBT.