Collective flip-chip technology for infrared focal plane arrays

After a description of the flip-chip technique developed at LETI, we present its main advantages and its evolution. Using this technique, a mass production procedure has been developed to decrease the cost of the technological step. With this method, we are able to simultaneously hybridize several linear or two-dimensional (2D) arrays directly onto readout circuits on silicon wafers, The electrical accessibility to the components provided by this method enables more detailed electrical tests to be carried out with an automatic prober before integration in cryogenic conditions, which is done only for good electrical devices. We have also developed a highly reliable method to hybridize a very large infrared focal plane array ( IRFPA). With this improved technique, 2D arrays can undergo several thousand 300 K-77 K cycles without any degradation.