The evaluation of SrBi2Ta2O9 films for ferroelectric memories

For use in ferroelectric memories, the layer structure ferroelectric SrBi2Ta2O9 (SET) appears to have some stability-related advantages over the more commonly known PZT class of ferroelectrics. Currently we are evaluating the feasibility of integrating this material into a state of the art CMOS memory process. Our primary scientific goal is to identify the intrinsic limitations of SET which may restrict the engineering applications of films grown jy even perfectly optimized processes. To this end we have utilized a wide variety of microanalysis probes to examine polycrystaline SET films grown under various conditions by both MOD and Flash MOCVD. We have found that X-ray diffraction methods must be supplemented by high resolution X-ray photoelectron spectroscopy (XPS) in order to fully analyze the secondary phases which are commonly incorporated in SET films. The more complete knowledge of film microstructure that this provides has enabled us to relate phase structure to growth and annealing conditions. XPS has also given us some insight into the initial stages of the growth chemistry of SET on various Pt surfaces.