Integrated Capacitors with Nb₂O₅ Dielectric for Decoupling Applications

Abstract

As electronic systems are scaling down further and further, there is the constant need to utilize all the board area with maximum efficiency. Since passive components occupy most of the space on boards, it is very important to scale them down. New techniques allow for “integrated” passives as opposed to their discrete counterparts. Integrated capacitors can be embedded within the substrate, leaving room for other components on the board surface. In order to improve the area efficiency of these integrated capacitors, researchers have formed multilayered capacitors in the past. This increases the capacitance density, but is time consuming and expensive due to too many process steps. With increased circuit density, a currently demonstrated dielectric, Ta₂O₅, could be replaced with a potential high-k dielectric that can store more charge in a smaller area than a capacitor with Ta₂O₅. Niobium pentoxide (Nb₂O₅) with k∼41 is an emerging dielectric for high-k capacitor applications. This paper investigates niobium pentoxide as a next generation high-k planar capacitor dielectric. Niobium pentoxide dielectric was formed by reactive sputtering and anodization. Dielectric characterization was done using X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscopy (TEM), and Atomic Force Microscopy (AFM). Thin film planar capacitor structures were fabricated using Nb₂O₅ dielectric and electrically characterized. The results presented include dielectric material characterization, design, capacitance, and breakdown voltage measurements.