Advanced 3-D stacked technology

Array sensors (e.g. focal plane array detectors) have densely aggregated cells to capture low energy levels that are converted into electrical signals. In hybrid assemblies, where focal plane arrays are bump-bonded to readout ICs, pixel density is being continually increased as processing and assembly technologies improve. Denser arrays, combined with extremely high frame rates (e.g. >106 frames/sec) create a formidable explosion in signal content. One approach to overcoming this issue is to move the signal processing closer to the array, minimizing the number of interconnects and the interconnect length the raw pixel signal outputs must travel prior to digitization, providing opportunity to buffer bursts (<64 frames) of high-rate collection sessions. One innovative approach to achieving this is to use 3D stacking of the pre-processing electronics for each pixel row directly behind the sensor array. This paper describes the development of a high density, 3D stacking technology that is being applied to an 8000-pixel array sensor cube that can eventually be scaled to mega-pixel densities through tiling.