Microstructure and dielectric properties of amorphous BaSm2Ti4O12 thin films for MIM capacitor

BaSm2Ti4O12 (BST) film grown at room temperature was amorphous, while the film grown at 300 °C was also amorphous but contained a small amount of crystalline Sm2Ti2O7 (ST). The crystalline BST phase was formed when the film was grown at 700 °C and subjected to rapid thermal annealing (RTA) at 900 °C. On the other hand, the ST phase was formed in the film grown at 300 °C and subjected to RTA at 900 °C. A high capacitance density of 2.12 fF/μm2 and a low leakage current density of 1.15 fA/pF V were obtained from the 150 nm-thick BST film grown at 300 °C. Its capacitance density could conceivably be further increased by decreasing the thickness of the film. It had linear and quadratic coefficients of capacitance of −785 ppm/V and 5.8 ppm/V2 at 100 kHz, respectively. Its temperature coefficient of capacitance was also low, being approximately 255 ppm/°C at 100 kHz.