Investigation on the electrical properties of the Ba2 Ti9 O20 thin films for metal-insulator-metal capacitor application

Homogeneous crystalline Ba2 Ti9 O20 (BT) phase was formed for the films grown at 700 and annealed at 900°C. However, BaTi5 O11 second phase was also developed for the films grown at temperatures lower than 700°C and annealed at 900°C. A high capacitance density of 6.1 fFμ m2 along with a leakage current density of 3.1× 10-8 A cm2 at 1.0 V were obtained for a 61 nm thick crystalline BT film. This film had small quadratic and linear voltage coefficients of capacitance (VCC) of -48.5 ppm V2 and 534 ppmV, respectively, and a small temperature coefficient of capacitance (TCC) of -465 ppm°C at 100 kHz. A 62 nm thick amorphous BT film grown at 300°C showed a high capacitance density of 5.5 fFμ m2 with a very low leakage current density of 0.59× 10-9 A cm2 at 2.0 V. This amorphous film also showed small quadratic and linear VCCs of 99.7 ppm V2 and 371 ppmV, respectively, with a low TCC of 661 ppm°C at 100 kHz. These results demonstrate that BT films, particularly amorphous BT films, are good candidate materials for metal-insulator-metal capacitors.