3 - Packaging related technologies

There are two different way to build electrical contacts between the two sides of a silicon wafer. In the thermomigration process aluminium-silicon alloy "drops" are forced to migrate toward the cold side of the wafer. The migration goes on anisotropically, so that conductive areas with very small diameter can be made. Deep diffusion technique uses the conventional way off diffunding dopants into the silicon, but it is applied on the booth sides. Since the diffusion is almost isotropic, the conductor width will be in the range of the wafer thickness.