The effect of intermediate anneal on the ferroelectric properties of direct-patternable PZT films

Abstract

The effect of intermediate annealing ambient was investigated for the preparation of thick direct-patternable lead zirconium titanate (PbZrxTi1-xO3; PZT, x = 0.52) films using photosensitive stock solution containing diethanolamine (DEA) as stabilizer and orthonitrobenzaldehyde (NBAL) as cross-linking agent by metal-organic deposition method. The intermediate anneal was done at 400degreesC; for 20 min under air or O-2 ambient. The intermediate anneal under O-2 brought almost complete removal of organic species, however after anneal under air, carbon and hydrogen atomic species as organic fragment remained in the film. This incomplete removal of organic fragments induced the grain growth of PZT film without influencing from Pt substrate and the formation of micro-voids on film surface during final anneal for the crystallization of PZT film with perovskite structure. The growth direction and surface microstructure of PZT film was revealed to highly affect on leakage, capacitance, fatigue, and piezoelectric properties of PZT film. For PZT film with intermediate anneal under O-2 a good piezoelectric property, d(33) = 336 pC/N was obtained with pneumatic loading method, and this film showed 26.2 muC/cm(2) of remnant polarization (P-r), 35.6 kV/cm of coercive field (E-c) and well-developed and saturated hysteretic loop. The dielectric constant was obtained as 1795 from the C-V measurement at 1 MHz and 40% of initial polarization value was remained after 10(9) switching cycles through bipolar square wave of +/-10 V at 500 kHz. From the comparison of physical and electrical properties of PZT films prepared with different intermediate anneal ambient such as O-2 or air, it can be said that the intermediate annealing condition is very important procedure to control the properties of PZT film for applying it to piezoelectric system devices. (C) 2004 Elsevier B.V. All rights reserved.