Abstract
Driven by the modern trend for miniaturization of the wireless communication and portable products, conventional inductors fail to fulfill the requirement. In order to miniaturize the dimension of power inductors and to increase conversion efficiency of DC-DC converters, high inductance and saturation current are necessary. Hence, it is crucial to employ high-permeability films to enhance the inductance and saturation current of power inductors. In this study, FeCoHfO/AlOx multilayers and FeHfN films were fabricated by dc reactive magnetron co-sputtering. Inserting the AlOx layers increases the permeability of the multilayers, which is beneficial to raise the inductance nearly 5 %. In addition, increasing N2 flow alters the structure of FeHfN films from amorphous-like to crystalline phases, affecting magnetic properties and permeability. With the optimum N2 flow of 1.2 sccm, high permeability (μ’ > 600 at 50 MHz) was obtained. The inductance and saturation current made of FeHfN films were greatly enhanced around 13 % and exceeded 2 A, respectively. To further integrate into DC-DC converters, FeHfN films were selected alongside with the power inductors. After integration, the higher inductance and saturation current efficiently suppresses the current ripple and enhanced the conversion efficiency of DC-DC converters. Therefore, the FeHfN films are promising for miniaturization of the inductors and DC-DC converters.