Berlin 2005 – wissenschaftliches Programm

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SYFS: Nichtflüchtige Festkörperspeicher

SYFS 4: Poster

SYFS 4.9: Poster

Samstag, 5. März 2005, 08:30–16:30, Poster TU C

Non-linear imprint behavior of ferroelectric PZT thin films — •P.J. Schorn, U. Böttger, and R. Waser — Institut für Werkstoffe der Elektrotechnik 2, RWTH Aachen University, Germany

Ferroelectric oxide thin film capacitors are promising candidates for non-volatile Ferroelectric Random Access Memories (FeRAMs) as they exhibit a switchable polarization. One of the most important failure-mechanisms of these capacitors is the imprint effect. In this contribution the imprint effect of Pb(Zr_0.3Ti_0.7)O₃ (PZT) thin films is investigated. The most crucial failure due to imprint is the voltage shift expected during the runtime of the device. Taking a closer look at the static and dynamic imprint reveals that the mean coercive voltage shift over the logarithmic value of elapsed time is non-linear. This is in contrast to the current imprint model in the literature that only explains a linear increase of the voltage shift over log(time). Hence, a simple linear fit will lead to a crucial error in the lifetime-estimations. Investigating the temperature dependence of the shift behavior within the single linear branches one can clearly calculate two different activation energies for the different regimes. The activation energies can be calculated to amount W_A = 98 meV for region I and W_A = 44 meV for region III. The possible physical nature of this imprint behaviour will be discussed.