Next Generation Integrated Magnetics: A Comprehensive Study on the Design, Simulation, Fabrication, and Characterization of 3D Magnetically Enhanced Microinductors

One of the primary limiting factors presently inhibiting device miniaturisation is the current roadblock posed by the large size of inductors employed in power processing units. The miniaturisation and integration of the inductor is a challenge requiring innovations in novel inductor topologies. This paper reports the design, modeling, and analysis of a novel vertical magnetic-core inductor structure: coaxial cross-section of copper conductor and a magnetic core surrounding it. To evaluate the performance of the proposed inductor structure, we considered a range of performance parameters: inductance, saturation current, DC ratio of inductance to resistance (Q_dc), AC quality factor (Q_ac), etc., which are essential figures-of-merit (FOM) of micro-inductors that are employed for energy storage in PwrSiP/PwrSoC applications. A novel two-dimensional graphical approach that correlates AC performance and DC performance is introduced.We derived an inductance model for the proposed structure. The measured relative permeability (μ_r) and the magnetic loss tangent (tan δ) of Co-Zr-Ta-B magnetic thin-films, developed in-house, are used to estimate the AC quality factor. Finally, the primitive structure of the proposed inductor is fabricated, and experimental results are presented to demonstrate that it is possible to realize the proposed structure in practice.