CONTROL OF ELECTRICAL-PROPERTIES OF ION-BEAM SPUTTER-DEPOSITED PZT-BASED HETEROSTRUCTURE CAPACITORS

Previous work on pulsed laser ablation-deposition (PLAD) and sol-gel s ynthesis has shown that the crystallographic orientation of ferroelect ric Pb(ZrxTi1-x)O-3 (PZT) films and electrical properties of PZT-based capacitors is controlled by the substrate and/or bottom electrode mat erial type. Similar control is obtainable with the ion beam sputter de position method. Also, a nonferroelectric phase that is nucleated duri ng processing on RuO2/MgO substrates can be reduced or eliminated by i nterposing a layer of PbTiO3 (PT) between the electrode and the PZT fi lm. The use of the PT layer and other proprietary modifications made t o the RuO2 bottom electrode result in a substantial reduction in the f atigue of these PZT-based capacitors. The fatigue resistance and low d e leakage current of these capacitors qualify their use in non-volatil e ferroelectric random access (FRAM) and dynamic random access (DRAM) memory devices.