A Novel Integrated Power Inductor With Vertical Laminated Core for Improved L/R Ratios

In this letter, a novel integrated power inductor with a vertical laminated NiFe magnetic core for improved inductance to resistance ratio (L/R) ratios is proposed and demonstrated. Both the windings and magnetic core are accommodated within a groove at the backside of a silicon substrate and connected to the front-side IC through vias for compactness. NiFe is used to increase the inductance, and vertical lamination is used to suppress the eddy current in the magnetic core and assist hard axis alignment. A 1-mm2 embedded inductor with 131-nil inductance and 60-mΩ dc resistance working in megahertz range is fabricated. The L/R ratio is increased by seven times compared with integrated inductors with similar area, making it suitable for portable electronics power conversion system-on-chip applications.