If you’re interested in learning more about the construction of magnetics-on-silicon, which is an enabling technology for power-supply-on-a-chip (PwrSOC), the PwrSOC website has some of the presentations online. (But first, to learn more about PwrSOC, the current issue of EDN has Power SOCs: A crazy idea that just might work.)

From the presentation’s slides, given by Dr. Terence O’Donnell of Tyndall Institute,  High-Efficiency Micro-Inductors on Silicon (pdf):

The Tyndall approach uses a single layer of racetrack-shaped copper coils sandwiched between layers of a magnetic material. Both the copper coil and the surrounding NiFe core are deposited by electroplating:

A cutaway view of the inductor:

An overview of the magnetics-on-silicon fab process:

(Looks simple, right? Everyone I speak with says that Tyndall is at the forefront of this process, and there are many gotchas lurking within these steps.)

All of these diagrams are taken from the paper, presentation slides, which you can at the paper link above and here.

Two papers are also available on the PwrSOC website:

Pre-publication APEC 2008 paper:

Microfabricated Inductors for 20 MHz Dc-Dc Converters

… and from Transactions on Power Electronics:

Magnetics on Silicon: An Enabling Technology for Power Supply on Chip