Silicon systems of the near future will require interconnection in all three dimensions. Tru-Si's ADP technology provides a simple way to manufacture them. The contact holes are made in the front side of the wafer, and an insulating layer of oxide is added to separate the silicon from the metal. After all front side processing is over, the wafer is simply thinned until the contacts are exposed. The ADP process etches the oxide so the metal is exposed, but it etches the silicon faster, so that the silicon remains insulated from the contacts in a very robust process.