Barrier layer at metal-ceramic interface in ferroelectric MIM structures

(Received 23 December 1992, revised 28 April 1993, accepted 3 May 1993)

Abstract
The influence of interfacial contact effects in a ferroelectric Metal-Insulator-Metal (MIM) structure is described. Lead Titano-Zirconate (PZT) material is deposited by a sol-gel technique on a platinum bottom electrode. Top electrodes are deposited after PZT annealing. The ferroelectric properties of the PZT (related to the hysteresis curve) are strongly dependent on the thermal treatments of both electrodes. Preannealing of the bottom electrode before PZT deposition, as well as post annealing of the top electrodes, lead to an improvement of the properties (increase in remanent polarization and in dielectric constant). This is explained by the suppression of the contact barrier at the interfaces between PZT and metal. The switching of the domains in the subsaturated regime of the hysteresis can be modelled by introducing a non ferroelectric barrier at the interfaces when the electrodes are not annealed.