Ultra wide band frequency characterization of integrated TiTaO-based metal-insulator-metal devices

The titanium tantalum oxide, TiTaO, was fully characterized in situ in an integrated metal-insulator-metal (MIM) configuration on a wide frequency band, from 1 mHz to 30 GHz. First, XPS and XRD analysis show that TiTaO dielectric is amorphous and presents Ti-O, Ta-O, and Ti-Ta bounds. Next, by using dedicated MIM test devices and a specific extraction procedure, both relative permittivity κ and loss tangent tan δ were extracted on the wide frequency band. The results show a dependence on both frequency and thickness. Conduction mechanism of ion impurities such as oxygen vacancies at very low frequencies (below 0.1 Hz), Maxwell-Wagner relaxations due to space charges at electrode interface (between 0.1 and 5 Hz), and dielectric grain boundaries or hopping (between 1 and 100 MHz) are underlined and studied with temperature measurements. The paper shows the usefulness of in situ wideband frequency measurements and that the dielectric permittivity of TiTaO in a 100 nm thick film is decreasing from 86 at 10 kHz to 20 at 10 GHz.