High-Performance Metal–Insulator-Metal Capacitor Using Stacked TiO₂/Y₂O₃ as Insulator

Metal-insulator-metal (MIM) capacitors with single TiO2and a TiO2/Y2O3stack as an insulator are explored in this letter. It is found that, at the process temperature higher than 400°C, TiO2MIM capacitors demonstrate a high capacitance density at the price of an unacceptably high leakage current and voltage coefficient of capacitance (VCC). On the other hand, with the process temperature of 500°C, TiO2/Y2O3MIM capacitors display desirable characteristics in terms of a large capacitance density of 32.2 fF/μm2, a low VCC of 3490 ppm/ V2, small frequency dispersion, and a low leakage current of 4.5 × 10-9A/cm2at -1 V. The Y2O3film not only provides a high dielectric-electrode band offset but also possesses high thermal stability against crystallization; both are important to suppress leakage current. In addition, the Y2O3film prevents a TiO2film from crystallization at 500°C due to the increased entropy caused by incorporated Y atoms, and the amorphous TiO2film offers a high κ value to achieve a large capacitance density without sacrificing leakage current and VCC.