A solid-state imager joined to an avalanche multiplier film with micro-bump electrodes

A highly sensitive solid-state imager has been made by connecting an avalanche multiplier film to a CMOS readout circuit via micro-bump electrodes. Optimization of the vapor-deposition conditions for the indium bump material made it possible for micro-bumps of 5 /spl mu/m diameter and 4 /spl mu/m height to be formed into a 2/3-inch matrix array of 380,000 pixels. A prototype imager was constructed with a 0.5-/spl mu/m-thick avalanche photoconductive film. Clear avalanche multiplication of about ten times was observed at an applied voltage of 75 V. The imager had a good resolution and no recognizable after-images.