Compositional and microstructural characterization of thin film lead zirconate titanate ferroelectrics
Abstract Recent interest in thin film lead zirconate titanate (PZT) ferroelectrics has been intensified by the possible applications of these materials to non-volatile random access memory devices. In general, these thin films have different properties when compared with bulk ceramics of the same composition (Zr:Ti ranging from 48:52 to 30:70). We have begun investigating the composition and microstructure of sputtered submicron PZT films via electron probe microanalysis (EPMA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Bulk analysis of various films (EPMA) shows reasonable agreement with the composition of the target (especially Zr:Ti ratios). SEM illustrates a variety of microstructures which primarily depend on target material, sputtering conditions and substrate morphology. Plan-view TEM has been used to investigate the grain orientation and morphology of the ferroelectric films. Grain size for PZT varies considerably from tens of nanometers to several hundred nanometers. The grain size depends on the composition of the films and the sputtering conditions. Cross-sectional TEM samples are being studied to determine the degree of abruptness of the various heterointerfaces in a device structure.