Electrodes for PbZr x Ti1 − x O 3 Ferroelectric Thin Films

Abstract

Interface‐related degradation problems in PbZr x Ti 1 − x O 3 (PZT) thin‐ film nonvolatile memories have led to the search for alternate electrode materials to replace the conventional metal electrodes. In this work, the suitability of ceramic electronic conductors [ e.g. , ruthenium oxide ( RuO 2 ) and indium‐tin‐oxide (ITO)] as contact metallization for ferroelectric PbZr x Ti 1 − x O 3 thin films has been investigated using techniques such as Rutherford backscattering spectrometry, x‐ray diffraction, and electron spectroscopy for chemical analysis. Thin films of RuO 2 and ITO were deposited onto Si substrates by reactive sputtering. Sol‐gel derived PZT thin films then were deposited onto the conducting oxides and the samples were annealed at various temperatures between 400 and 700°C. Less intermixing was observed in Si / RuO 2 / PZT films when compared to Si/ITO/PZT under similar processing conditions. The ferroelectric properties of PZT films (hysteresis, fatigue, and low voltage breakdown) on RuO 2 electrodes were compared to those on Pt electrodes. PZT films show improved fatigue properties on RuO 2 electrodes. The films on RuO 2 electrodes also showed better current‐voltage characteristics (I–V) and time‐dependent dielectric breakdown properties (TDDB).