Investigation on the electrical properties of the Ba2Ti9O20 thin films for metal-insulator-metal capacitor application

Homogeneous crystalline Ba2Ti9O20(BT) phase was formed for the films grown at 700 and annealed at 900 degrees C. However, BaTi5O11 second phase was also developed for the films grown at temperatures lower than 700 degrees C and annealed at 900 degrees C. A high capacitance density of 6.1 fF/mu m(2) along with a leakage current density of 3.1x10(-8) A/cm(2) 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/V-2 and 534 ppm/V, respectively, and a small temperature coefficient of capacitance (TCC) of -465 ppm/degrees C at 100 kHz. A 62 nm thick amorphous BT film grown at 300 degrees C showed a high capacitance density of 5.5 fF/mu m(2) with a very low leakage current density of 0.59x10(-9)A/cm(2) at 2.0 V. This amorphous film also showed small quadratic and linear VCCs of 99.7 ppm/V-2 and 371 ppm/V, respectively, with a low TCC of 661 ppm/degrees C at 100 kHz. These results demonstrate that BT films, particularly amorphous BT films, are good candidate materials for metal-insulator-metal capacitors. (c) 2007 The Electrochemical Society.