Evaluation of the electrical and physical properties of thin calcium titanate high-$k$ insulators for capacitor applications

Thin calcium titanate $(CaTiO3)$ films are investigated as promising insulator materials with very high-$k$ values for future microelectronic devices such as metal-insulator-metal (MIM) capacitors and field-effect transistor gate stacks. MIM stacks were deposited by sputtering under UHV conditions without breaking vacuum. A capacitance equivalent thickness of 1.3 nm with a leakage current density of $1×10−7A/cm2$ at 1 V was achieved with deposition temperatures of $550°C$ on Pt as bottom electrode. The effect of different electrode materials was studied, resulting in leakage densities correlating directly to the different work function values. grazing incidence x-ray diffraction and high-resolution transmission electron microscopy images are analyzed to study the crystallization behavior. As grown $CaTiO3$ at $550°C$ exhibits crystallites in an amorphous matrix. A dielectric constant of $k≈93$ was obtained for crystallized films.