Robustness of carbon nanofiber-based MIM capacitors with ultra-high capacitance density to electrical and thermal stress

In this paper, we present carbon nanofiber (CNF)-based capacitors in a MIM configuration, a CNF-MIM, with a small footprint, low profile height, and high capacitance density that can be used both as integrated and as discrete component. Being produced in a fully CMOS compatible process it is likely to play a major role as further miniaturization of future electronics moves on. The devices were characterized from 25 °C to 150 °C and from 0 V to 5 V. It was demonstrated that a CNF-MIM with a total CNF height of 6 μm achieved a capacitance density of about 400 nF/mm
²
. Also shown was an ESR of about 45 mΩ. It was found that the capacitance increased slightly with temperature by 0.03-0.06 %/K and that the capacitance was stable for biasing voltage with an increase between 0.5-4 %/V. Hence, it meets well with the X7R specifications. This behavior makes it a good competitor compared to MLCCs whose capacitance decreases with temperature and applied voltage and the CNF-MIM does this at the fraction of the device thickness of the MLCC.