Leakage and interface engineering in titanate thin films for non-volatile ferroelectric memory and ulsi drams

Abstract

The leakage behavior of Pb(Zr,Ti)O₃ PZT and (Ba,Sr)TiO₃ (BST) thin films has been studied. The leakage behavior is dependent upon the bottom electrode. PZT films on RuO₂ bottom electrodes display a large leakage, predominantly ohmic in behavior, which we have shown to be PZT microstructure-controlled. The leakage of PZT and BST films on Pt display Schottky emission characteristics which is controlled by the film/electrode interface. In the case of PZT films, we have shown that several methods can be utilized to successfully lower the RuO₂/PZT/RuO₂ system leakage, while retaining the long term performance. These methods include pre-annealing of RuO₂ bottom electrode prior to PZT film deposition; addition of buffer layer between RuO₂ and PZT film; and PZT film growth via in-situ ion beam sputter-deposition.