A semiconductor component includes a base die and a secondary die stacked on and bonded to the base die. The base die includes conductive vias which form an internal signal transmission system for the component, and allow the circuit side of the secondary die to be bonded to the back side of the base...http://www.google.com.au/patents/US6841883?utm_source=gb-gplus-sharePatent US6841883 - Multi-dice chip scale semiconductor components and wafer level methods of fabrication
