3D Heterogeneous Package Integration of Air/Magnetic Core Inductor: 89%-Effi- ciency Buck Converter with Backside Power Delivery Network

Abstract

We demonstrate a novel concept of integrating $110-\mu \mathrm{m}$. thick low-resistance high-Q magnetic core inductors in fan-out wafer level packaging (FOWLP). Unlike thin-film magnetic core inductors [1], this solution offers the possibility to embed thick cores to meet power density requirements, allowing for 89% efficiency at 1.2 W /mm2 power density for 2: 1 power conversion with a backside power delivery network (BSPDN) using circular-shaped magnetic inductors.