Growth and characterization of epitaxial ferroelectric PbZrxTi1-xO3 thin film capacitors with SrRuO3 electrodes for non-volatile memory applications

Non-volatile FeRAMs based on thin film ferroelectric capacitors are emerging as an advantageous replacement for EEPROM and flash devices. In this work, ferroelectric Al/PbZrxTi1-xO3 (PZT)/SrRuO3 thin film capacitors were fabricated and its suitability for memory applications was tested. The PZT films, as well as the SrRuO3 bottom electrodes have been grown by pulsed laser deposition on LaAlO3(0 0 1) substrates. Epitaxial heterostructures with high crystalline quality were obtained. Top aluminum electrodes were thermally evaporated onto the PZT films. High dielectric constant of 700 and dielectric loss tangent of 0.03 were obtained. Good ferroelectric behavior with an activation field for switching gamma = 308 kV/cm and a low coercive voltage of 1.1 V at 40 Hz was observed. The reliability of the thin film capacitors has been tested by means of pulse switching measurements. The polarization shows very little fatigue with cumulative switching. Built-in imprint, arising from the use of asymmetric electrodes, along with induced imprint related to charge trapping at the interfaces were observed. (C) 2001 Elsevier Science Ltd. All rights reserved.