Multilayer lead zirconate titanate and barium titanate ferroelectric capacitors

Ferroelectric PbZr_xT_1-xO₃ (PZT) thin films have been deposited on Pt coated Si substrates by rf magnetron sputtering. The optimized processing condition to obtain proper stoichiometric PZT, the desired ferroelectric perovskite phase, and better dielectric properties was demonstrated using a PZT target with Pb(Zr+Ti) ratio of 1.2 and depositing at 350 °C, followed by thermal treatment at 620 °C for 30 min. The structural and electrical properties of the PZT layer were further improved by fabricating a novel multilayer structure which combined the PZT with the nanolayer BaTiO₃. The leakage current density was reduced from 2×10^-7 A/cm² for the single layer structure to 2×10^-9 A/cm² for the multilayer structure at a field of 4×10⁵ V/cm, while maintaining a high relative effective dielectric constant of 442. The relative dielectric constant of the PZT film in the multilayer structure was calculated to be about 880.