A novel integrated power inductor in silicon substrate for ultra-compact power supplies

Abstract

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.

Polymer Magnetic Composite Core Based Microcoils and Microtransformers for Very High Frequency Power Applications

“…In addition, the binder material should have a low viscosity, a high glass transition temperature ( ), long pot time (the time it takes to double the initially mixed viscosity), low curing temperature, and a high Young’s modulus. Based on the study of various publications [ 23 , 24 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ] and intensive search for commercial availability, suitable polymers have been identified which are listed in Table 2 .…”

Modeling and Measured Verification of Stored Energy and Loss in MEMS Toroidal Inductors

“…Because the two magnetic fields and the two current densities are spatially orthogonal, their cross products are not present in the generalization of (13) and (14). Therefore, (13) and (14) may be used twice to determine the stored magnetic energy and loss for each conductor, once for the toroidal magnetic fields and the poloidal currents, and once for the poloidal magnetic fields and the toroidal currents.…”

“…It is important to observe that (17)- (19), (21) and (22) all involve the same approximation. In particular, (13) and (14) are developed for a conductor assuming uniform fields over y and z. That is, H y at the winding surface is uniform in Fig.…”

“…On-chip inductors that are built for power converters in the multimegahertz range using MEMS-like microfabrication are studied in the works in [3]- [13] and are reviewed in [14]. With a sufficiently small volume, the magnetics can be embedded in the substrate of the power circuit or within a secondary substrate, and can be flip bonded above the power circuit.…”

High Temperature Magnetic Cores Based on PowderMEMS Technique for Integrated Inductors with Active Cooling

“…In [ 1 , 5 , 6 , 7 ], several processes and designs of inductors on silicon wafers were discussed, but mainly the windings were placed on the surface like spiral inductors. Towards further device integration, 3D-inductors were developed with an air core and through-silicon vias (TSVs) in [ 8 , 9 ].…”