Low-temperature fabrication of epitaxial and random-oriented Pb(Zr,Ti)O 3 capacitors with SrRuO 3 electrodes on Si wafers

Epitaxial and random-oriented Pb(Zr,Ti)O 3 (PZT) films were fabricated at 450-550°C on SrRuO 3 (SRO)/SrTiO 3/Si and SRO/amorphous Ti-Al layer-Si substrates, respectively, using a modified sol-gel process. For comparison, polycrystalline PZT films were also prepared on Pt-Si substrates using the same method. Thermogravimetric and differential thermal analysis (TG-DTA) of the modified sol-gel solution indicated that the solution began crystallization below 400°C. Both SRO/epitaxial PZT/SRO and SRO/random-oriented PZT/SRO capacitors processed at the same temperature had similar polarization values, and all the SRO/PZT/SRO capacitors processed at 450-550°C exhibited the favorable electrical characteristics including high polarization, high resistivity, small pulse width dependence, and good fatigue endurance. While the Pt/PZT/Pt capacitors processed at 450°C showed considerably low polarization compared to the SRO/PZT/SRO capacitors processed at the same temperature. High-quality SRO/PZT/SRO capacitors processed at low temperature have a bright prospect of fabrication of potential Si devices integrated PZT capacitors without thermal degradation.