Analyses of Pt/Ti Electrodes for Plzt Capacitors

Abstract

AbstractA suitable choice of an electrode material is important for an acceptable electrical contact to a high-permittivity dielectric, such as PLZT. A material which does not form a low-permittivity oxide is necessary, since these dielectrics generally require high temperature deposition or annealing in an oxidizing environment. Platinum, which is one of the few metals that satisfy this requirement, has been widely employed for contacting PLZT. However, for integrated circuit applications, an adhesion layer must be superposed between Pt and the substrate, and Ti is used frequently. Therefore, we have investigated the Pt/Ti combination to determine its suitability as an electrode for contacting PLZT. Using x-ray diffraction, Rutherford backscattering spectrometry, Auger electron microscopy, and scanning electron microscope techniques, interdiffusion of Pt/Ti bilayers has been investigated. Pt/Ti films with or without PLZT overlay were annealed in either O2 or N2 ambients or in N2 followed by O2. Annealing temperatures varied from 500 to 800 °C. It was observed that the anneal ambient has a marked effect on the interdiffusion processes, the reaction products, the morphology of the structures, and the crystallization of PLZT.