Developments in integrated on-chip inductors with magnetic yokes

Abstract

Thin-film ferromagnetic inductors show great potential as the energy storage element for integrated circuits containing on-chip power management. In order to achieve the high energy storage required for power management, on-chip inductors require relatively thick magnetic yoke materials (≥ a micron). The first part of this paper includes a review of on-chip inductors with magnetic materials from earlier studies. The second part describes the fabrication and characterization of a magnetic inductor on a silicon interposer at IBM. These inductors contained a variety of yoke geometries, included single-turn and multi-turn coils, and were fabricated on 200mm silicon wafers in a CMOS back-end-ofline (BEOL) facility. Each inductor consisted of electroplated copper coils enclosed by electroplated Ni45Fe55 yokes. Aspects of the fabrication of the inductors are described, along with the magnetic properties of the electroplated yoke material and inductor performance. © The Electrochemical Society.