Electrical properties of Pb(Zr0.53Ti0.47)O-3 thin film capacitors with modified RuO2 bottom electrodes

Growth of Pb(Zr0.53Ti0.47)O-3 (PZT) thin films on RuO2 electrodes by the sol-gel process is usually accompanied by the formation of second phases. The resulting RuO2/PZT/RuO2 capacitors are fatigue-free up to nearly 10(11) switching cycles, but they have high leakage currents (J similar to 10(-3) A/cm(2) at 1 volt) and large property variation. We have developed several modifications of the RuO2 bottom electrode which enhance nucleation of the perovskite phase, eliminate or reduce the second phases, and control film orientation and properties. The PZT films deposited on the modified RuO2 electrodes have leakage current densities which are two to four orders of magnitude lower than those of PZT films deposited on the unmodified RuO2 electrodes. In most cases, the excellent resistance to polarization fatigue which is characteristic of the RuO2/PZT/RuO2 capacitors, is maintained.