Abstract
High permeability magnetic films can enhance the inductance of thin-film inductors in DC-DC converters. In order to obtain high permeability, uniaxial anisotropy and coercivity should be as low as possible. This study employed dc reactive magnetron sputtering to fabricate the nanocrystalline FeHfN thin films. The influence of nitrogen flows on composition, microstructure, permeability characteristics, as well as magnetic properties was investigated. Increasing nitrogen contents can alter the FeHfN films from amorphous-like to crystalline phases, and the magnetic properties and permeability depend on the variations of microstructures. With this optimum condition of the nitrogen flows at 1.2 sccm, low anisotropy (H <sub>K</sub> 20 Oe), low coercivity (H <sub>C</sub> 1.1 Oe) and permeability (μ' > 600 at 50 MHz) were obtained for the nanocrystalline FeHfN film with a thickness around 700 nm. The as-fabricated FeHfN films with permeability over 600 at 50 MHz should be promising for high-permeability ferromagnetic material applications. © Published under licence by IOP Publishing Ltd.