Results of tests of three-dimensionally integrated chips bonded to sensors

The VIPIC1 pixel readout integrated circuit was designed for high timing resolution, pixel based, X-ray Photon Correlation Spectroscopy experiments, typically using 8 keV X-rays at a synchrotron radiation facility. Technical hurdles related to a very aggressive alignment resulted in delays with delivery of 3D bonded wafers that eventually yielded operational devices. Recent improvements in alignment of wafers bonded with the Cu-Cu thermo-compression method and resorting to the Cu-DBI® bonding method started providing operational devices that were tested and led to the next steps. These were the tests with radioactive sources, emitting X-rays, executed after bonding of individual 3D dies to Silicon pixelated sensors for the first time. Results of these tests are presented.