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

Abstract

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.