A three-dimensional architecture for a parallel processing photosensing array (silicon retina application)

A three-dimensional architecture for a photosensing array has been developed. This silicon based architecture consists of a 10*10 array of photosensors with 80- mu m diameter, through-chip interconnects to the back side of a 300- mu m*300- mu m pn-junction photodiode. The following processes were used to create this photosensitive architecture: (1) thermomigration of aluminum pads through an n-type silicon wafer; (2) creation of pn-junction photosensors on one side of the wafer; and (3) creation of aluminum pad ohmic contacts to the thermomigrated, through-chip interconnects and the substrate on the back side of the wafer. The electrical and optical characteristics of the three-dimensional architecture indicate that it should be well suited as a photosensing framework around which a ´silicon retina´ could be built.