Role of Interface Reaction at High Temperature in Electrical Characteristics of Bi_3.25La_0.75Ti₃O ₁₂/Al₂O₃/Si Capacitors

A novel face-to-face annealing process was used to investigate the enhanced electrical characteristics in Bi_3.25La_0.75Ti ₃O₁₂ (BLT)/A1₂O₃/Si capacitors annealed at high temperatures. The low leakage current of BLT/A1 ₂O₃/Si capacitors can be obtained after high temperature annealing and the mechanism has been clarified and attributed to the formation of Si-rich, aluminum oxide. The surface composition of aluminum oxide after annealing was further analyzed by X-ray photoelectron spectrometer (XPS) and XPS spectra revealed that the aluminum oxide would react with both Si substrate and BLT thin films to form Si-rich aluminum oxide. Because the aluminum oxide has weaker bonding than that of silicon oxide, Si composition can quench the electrical defects in aluminum oxide so as to reduce the leakage current of BLT/A1₂O₃/Si capacitors.