EFFECT OF SUBSTRATE-TEMPERATURE ON ELECTRICAL CHARACTERISTICS OF (PB,LA)(ZR,TI)O-3 ULTRATHIN FILMS DEPOSITED BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

Lanthanum-modified lead zirconate titanate (PLZT) thin films (50-200 nm) were deposited on Pt/SiO2/Si substrates by metalorganic chemical vapor deposition (MOCVD). The electrical properties of the films were investigated as functions of the La content and substrate temperature. Ferroelectric PZT films were obtained at a substrate temperature as low as 500 degrees C, and their electric characteristics were improved with increasing substrate temperature. La was adequately solid-dissolved into the PZT above 650 degrees C. PLZT(15/45/55) films having a thickness of 100 nm were found to have good properties for application to capacitors of dynamic random access memory (DRAM), i.e., effective charge density of 80 fF/mu(2), dielectric constant of 1000. SiO2 equivalent thickness of 0.4 nm and leakage current density of 5x10(-8) A/cm(2). La addition to PZT was effective in reducing the leakage current with an increase in the registration rate.