Fabrication of ferroelectric SrBi2Ta2O9 capacitor films using plasma-assisted metalorganic chemical vapor deposition and their electrical properties

The fabrication of SrBi2Ta2O9 (SBT) films using plasma-assisted metalorganic chemical vapor deposition (P-MOCVD) has been investigated. Optimizing the process conditions under plasma environment, amorphous SBT films were successfully deposited at a substrate temperature below 300 °C, suggesting that the P-MOCVD process effectively utilizes plasma energy to promote the reaction and decomposition of metal organic source molecules. The amorphous SBT films were crystallized to the bilayered perovskite SBT films by a postannealing at 725 °C. Thin SBT capacitors fabricated using P-MOCVD showed a good step coverage and the excellent ferroelectric properties including endurance. Low voltage operation below 1.5 V was successfully achieved using a 75 nm SBT capacitor, in which the signal level derived from the hysteresis curve suggests the feasibility of application to a 64 Mbit ferroelectric random access memories.