Interdiffusion phenomena in SrBi₂Ta₂O₉ films

Abstract

Mass and Energy Dispersive Heavy Ion Recoil Spectrometry (RS) employing 75.6 MeV ¹²⁷I ions has been used to analyse thin films of strontium bismuth tantalate (SBT) at the heavy ion recoil facility at ANSTO, Lucas Heights. The new ferroelectric material ‘Y1’, SrBi₂Ta₂O₉ or SBT, has been developed for application in memory chips due to its excellent fatigue resistance. In other ferroelectric films developed for similar applications, e.g. Ba_xSr_1−xTiO₃ or BST¹, there has been evidence of interdiffusion during the annealing process of the films. This study uses RS to determine the amount of interdiffusion in a standard treatment of SBT deposited on a Pt electrode on a Si substrate with a Ti adhesion layer. Depth profiles for all major elements and carbon have been obtained. Analysis reveals no depletion of oxygen in the SBT layer closest to the platinum electrode.