A magnetic induction coil is mounted directly on and integrated with a semiconductor wafer containing integrated circuitry for a stable power source. Grooves are etched in the reverse face of the wafer substrate, an insulating film is applied, and conducting material fills the grooves, forming the coil....http://www.google.com.au/patents/US5519582?utm_source=gb-gplus-sharePatent US5519582 - Magnetic induction coil for semiconductor devices
