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

Abstract

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 1×10−7 A/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.