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 b ismuth is reported. Rapid ther mal annealing initiates the crystallization of bismuth layer-structured ferroelectric thin films. Subsequent crystalliz ation annealing for longer periods improves the crystallinity of the thin f ilms. 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 a nnealing) reduces the bismuth diffusion into the electrode significantly. T he suppression of bismuth diffusion into the electrode and the elimination of excess bismuth in the films improves and stabilizes the electrical prope rties of the capacitors, in particular their electronic conduction.