High capacitance density metal-insulator-metal structure based on Al2O3–HfTiO nanolaminate stacks

The authors describe metal-insulator-metal (MIM) capacitors comprising a five layer Al2O3–HfTiO nanolaminate stack with a total thickness of ∼29nm. At room temperature they demonstrate a capacitance density of ∼14fF∕μm2, a leakage current density of ∼1×10−6A∕cm2 at 1V, a temperature capacitance coefficient of 380ppm∕°C as well as corresponding linear and quadratic voltage coefficients of 350ppm∕V and 570ppm∕V2, respectively. They compare the structure to a MIM capacitor having a uniform HfTiO insulator film. That device exhibits a larger capacitance density (∼28fF∕μm2) but its electrical properties are found to be poorer than those of the structures utilizing the nanolaminate stack.