Enhancement of inductance and quality factor in GHz range of solenoid inductor by integrating [Fe80Ni20-O/SiO2]n magnetic multilayer films

With the rapid development of science and technology, the demands for miniaturization, integration and high frequency of the electromagnetic devices were steadily increased. The integrated inductor is an important passive component for RF devices such as power transformers, amplifiers and oscillators. However, the performance of on-chip integrated inductors was poor when operating in GHz band. It is well known that, the integration of a magnetic material as magnetic core can effectively improve the performance of inductors [1]. The normal magnetic materials have very lower resonance frequencies (f_r), which can´t meet the demand of the high frequency inductance components. But if the magnetic films have in-plane uniaxial magnetic anisotropy, the f_r can be exceeded 1 GHz [2]. According to the theoretical calculation results, when serving as magnetic core in solenoid inductor, the magnetic films need to hold excellent soft magnetic performance even for the thickness of the film larger than 200 nm. For high frequency soft magnetic monolayer films and granular films, the high frequency magnetic performance are degenerated drastically because of strong inner stress and large grain size when the film thickness increases to a few hundreds of nanometers. Based on our previous study, the multilayer technology can help to maintain good high frequency soft magnetic properties even though the film is very thick [3]. Therefore, the [Fe₈₀Ni₂₀-O/SiO₂]_n multilayer magnetic film was selected as magnetic core to fabricate the on-chip integrated solenoid inductor and improve the performance of the inductor.