Investigation of a bump bonding interconnect technology for GaAs pixel detectors

Pixel detectors made of semi-insulating GaAs have already been successfully tested for their application as tracking detectors in high energy physics experiments. For the operation of large arrays of pixel sensors, a technology allowing a two-dimensional interconnect with a high yield is necessary. For this purpose a bump bonding process was developed. In this paper the, yield and the resistance of the interconnections is analyzed. With more than 2700 interconnections on special test structures the resistance of a single bump-bond is consistent with zero Ohm and the yield was determined to be 92%.