Grain size and orientation analysis of SrBi2(Ta,Nb)2O9 films by electron backscatter diffraction

The orientation of polycrystalline ferroelectric films used in ferroelectric random access memories (FeRAMs) has a significant influence on the electrical properties. In particular, the polarization of ferroelectric SrBi₂Ta₂O₉ (SBT) and SrBi₂(Ta,Nb)₂O₉ (SBTN) films strongly depends on the crystal orientation because these films polarize only along the a-axis as stated in Y. Shimakawa et al. (1999), For instance, an x-ray diffraction measurement indicated that an SBT film deposited on an (111)-oriented platinum plate tends to preferentially grow along the c-axis as the average grain size increases as presented in C. Bae et al. (1999). In view of the scaling limit of FeRAMs governed by the grain size, it is crucial to obtain information on whether the entire film is oriented along the c-axis preferentially or c-axis-oriented grains have grown exclusively. We have investigated the relationship between the grain size and the crystal orientation of individual grains of SBTN films, for the first time, via electron backscatter diffraction (EBSD) technique as presented in A. J. Schwartz et al. (2000) and B. L. Adamus et al. (1993).