Process optimization and characterization of device worthy sol-gel based PZT for ferroelectric memories

The purpose of this work is to develop and characterize an optimized sol-gel PZT process to be used in ferroelectric memories. A review of the sol-gel process is given, including discussions on hydrolysis under acidic and basic conditions. Application of the sol-gel process to thin films is then discussed. Topics such as removal of solvents, stresses in the thin film and how this relates to cracking are mentioned. A review of different synthesis methods of sol-gel PZT is then conducted in order to help determine a device worthy sol-gel PZT process. Methods of controlling the pore size by hydrolysis and different heat treatments at various stages during the drying and annealing cycles are then used. The quality of thin film PZT on Pt is characterized by using dispersive X-ray and X-ray diffraction analyses. Electrical results yield Pr ranging from 7.9-21.9 μC/cm2Ec ranging from 29.1 -92.3 kV/cm and switching times as fast as 56 ns, using a capacitor area of 1 × 104 μm2. However, these results depend on the stoichiometry and method of measurement used. Fatigue curves show a single time constant switching charge decay which may be indicative of a single type of defect domain interaction.