Application of nanocrystalline FeHfN soft magnetic films to power inductors

Abstract In the communications industry, miniaturization is a requirement for inductor devices. To miniaturize power inductors, high inductance is necessary. To this end, high-permeability FeHfN magnetic films are used to enhance the inductance of power inductors. These nanocrystalline FeHfN soft magnetic films, each roughly 700 nm thick, were deposited onto Si substrates using nitrogen reactive sputtering. In this study, planar sandwiched power inductors containing FeHfN films have a higher inductance than air-core power inductors. Inductance ( L ) of high-permeability FeHfN films is enhanced significantly by roughly 13% compared with that of air-core inductors at 5 MHz. Integrating power inductors with FeHfN films may increase extra parasitic capacitance. Moreover, the increased eddy current loss is created by the low resistivity of FeHfN films. Therefore, the quality factor ( Q ) of sandwiched power inductors decreases at 5 MHz. Conversely, saturation current ( I sat ) of these planar sandwiched power inductors exceeds 2 A. Such planar power inductors with the high-permeability FeHfN films are a promising candidate for applications in DC–DC converters.