Comparison of CSD and sputtered PZT with iridium electrodes

Abstract

Several recent reports have combined Ir electrodes with PbZr_xTi_1−xO₃ (PZT) made by chemical solution deposition (CSD) to produce capacitors with low fatigue rates, but the same behavior has not been reported for sputtered PZT with Ir electrodes. This paper presents a comparison of the performance of sputtered and CSD PZT capacitors with Ir electrodes. It was found that replacing the Pt top electrode with Ir was sufficient for obtaining improved fatigue performance for both sputtered and CSD deposited PZT. A comparison of Ir and Pt top electrodes shows that Ir can extend the number of useful switching cycles by 3 to 4 orders of magnitude for both sputtered and CSD deposited PZT. As has been previously observed for Pt electrodes, the fatigue with Ir top electrodes is dependent on the switching voltage. Excellent fatigue performance has been observed to 10¹¹ cycles for both 3 and 5 V switching potentials. In addition to fatigue performance, a detailed analysis of switching, retention and leakage current behavior will also be presented.

Key Words:

• PZT
• iridium
• hydrogen degradation
• ferroelectric
• thin films