A Novel Integrated Power Inductor in Silicon Substrate for Ultra-Compact Power Supplies

摘要

A novel silicon-based inductor, power inductor in silicon, or PIiS, has been proposed and experimentally demonstrated. The PIiS is fabricated at wafer level using a silicon molding micromachining technique, in which 200 μm thick copper windings are embedded into a silicon substrate and both sides of the substrate are capped with a polymer-magnetic power composite. Through-silicon vias (TSVs) and copper routings are also added so that a PIiS can be directly used as a surface mountable packaging substrate. A 3×3×0.6 mm~3 PIiS with a measured inductance of 390 nH has been fabricated. The Q factor of this PIiS is 10 at 6 MHz. An ultra compact buck converter has been made by surface mounting off-shelf power ICs and capacitors on a PIiS. The buck converter is 3×3×1.2 mm~3, which has successfully delivered 500 mA at 1.8V with an 80% efficiency at 6 MHz.