A novel fabrication method for stoichiometric strontium bismuth tantalate thin films for memory devices

A novel method of processing ferroelectric thin films to eliminate excess bismuth is reported. Rapid ther mal annealing initiates the crystallization of bismuth layer-structured ferroelectric thin films. Subsequent crystallization annealing for longer periods improves the crystallinity of the thin films. During annealing bismuth is known to diffuse to the surface and into the electrode, which is deleterious to the device performance. Forming-gas annealing after the rapid thermal annealing (prior to the crystallization annealing) reduces the bismuth diffusion into the electrode significantly. The suppression of bismuth diffusion into the electrode and the elimination of excess bismuth in the films improves and stabilizes the electrical properties of the capacitors, in particular their electronic conduction.