High-Performance MIM Capacitors With Nanomodulated Electrode Surface

We report on a high-performance metal-insulator- metal (MIM) capacitor using a barrier-type anodic alumina as dielectric and exhibiting a capacitance density as high as 10 fF/μm² with leakage current density lower than 10^-8 A/cm². The device is shown to be very stable in terms of frequency, showing a capacitance variation less than 3% in the frequency range between 10³ and 10⁶ Hz. A loss tangent <;0.1 is shown for the anodic alumina used. Moreover, by introducing nanomodulation to the capacitor electrode, the effective surface area of the capacitor is increased, allowing the use of thicker dielectric layers for the same value of capacitance density. The use of thicker dielectric layers is shown to decrease the leakage current by an order of magnitude and the nonlinearity coefficient α by a factor of 1.8 for the larger capacitance density devices. These results suggest a novel strategy for reducing the α coefficient of a MIM capacitor without decreasing the capacitance density.