Design and fabrication of thin film inductors using closed laminated core for 20‐MHz DC–DC converters

Abstract

This letter presents a feasible and cost-effective approach to realize closed laminated core, which is used to realize on silicon integrated thin film inductors. The closed laminated core is fabricated by electroplating magnetic layers with an oxide insulation layer sputtered in-between. This is compatible with the back end of line (BEOL) processes. The prototype of the thin film inductor with closed laminated core shows less degradation of AC inductance and smaller AC resistance at high frequencies than the variant with a solid core. Furthermore, it is tested in a 20-MHz DC–DC converter. The peak efficiency of 80% was achieved.