Ferroelectric PZT is one of the well known functional materials that has a great deal of potential as a non-volatile memory device. It is expected that the PZT will improve the limitation in the storage density encountered in the conventional Si memory technology. However, the PZT shows some undesirable properties that affect the reliability of ferro-electric memory devices such as fatigue, retention, imprint, leakage current, TDDB etc.. In the present study the leakage current and micro-structure of PZT thin films have been investigated to understand the mechanism of leakage current and attempt to find ways to improve the leakage characteristics. The PZT thin film samples were prepared using sol-gel process followed by crystallizing in three different gas atmos-phere,i.e. $N_2$, air, and $O_2$. Each crystallized sample shows different microstructure and orientation, which were analyzed by SEM and XRD. Depth profiling was also performed to examine the compositional distri-bution of each element of PZT throughout the thickness of the films. Electrical characterization of the PZT thin films including the permit-tivity, P-E hysteresis, and the leakage current were carried out. The permittivity of the sample was found to increase in the order of $O_2$,air, and $N_2$ treatment, while the remnant polarization was decreased. It is also found that the leakage current was affected not only by the microstructures of the films but also the interface between Pt electrode and the PZT film. Moreover, it was found that more than one conduction mechanisms are observed in the range of E field used in the experiment. In the low E field region the current conduction is ohmic and its mechanism is found to be the electron hopping among the electron traps. In the high field region the sample treated in $N_2$ shows the Schottky emission, the one treated in $O_2$ shows the space charge limited conduction, and the sample treated in air shows both the Schottky and the space charge conduction together.
