Modeling and validation of ESR and frequency-stability of high-density nanostructured capacitors for embedded power converters

Increasingly dense microprocessors will require high-density passive components that can enable integrated power delivery with larger conversion ratios and higher output currents. Of these, nanoparticle-based tantalum capacitors can provide some of the highest volumetric densities compared to other capacitor technologies, due to the high surface area-to-volume ratio. Additionally, their temperature-stable dielectric can handle higher current ratings. However, the complex nanoparticle-based electrode structure results in long conduction paths, resulting in higher ESR and reduced frequency stability. A model is needed that can accurately predict the relationship between capacitor nanostructure and electrical performance so that the nanostructure can be optimized to meet the theoretical limits of device performance. This paper develops such a model, and demonstrates its accuracy by characterizing a real tantalum capacitor device. The model is then used to study the effect of capacitor materials and device geometry on the device performance, including capacitance density, frequency stability, and ESR.