Disruptive techniques for hybridization of focal plane arrays for optical imaging sensors

This work is focused toward developing disruptive hybdrization techniques for imaging focal plane arrays in which the optical detector material system is different from the silicon material used for processing, amplifying and reading out the opto-electronic signals. In these cases, the detector pixels need to be interconnected to the electronic pixels through a process called hybridization. This process has traditionally been performed through the use of high precision, high stiffness flip chip bonders, which are expensive to procure, operate and maintain. Additionally, as defense needs drive imaging arrays to better resolution, these hybridization platforms will need to evolve. The supply base for this equipment base has shrunk dramatically, and are non-U.S. based, creating a gap for development of next generation, higher resolution arrays as well as maintaining and scaling production of the current generation of arrays. The disruption pursued in this work is to use micro-machined and micro-fabricated features to enable precision alignment and hybridization of imaging arrays, using standard pick & place machines with modest levels of precision. This is achieved through use of alignment structures at the periphery of the array that can provide a rough level of alignment. The self aligning action of the solder in the pixel areas achieves the final precision alignment during reflow. BENEFIT: The work benefits production of the current generation of imaging focal plane arrays in the SWIR, MWIR and LWIR wavelength ranges. It also enables development of the next generation of imaging arrays at increased levels of resolution (and reduced levels of pixel pitch)in the material systems used for these wavelengths. It addresses a critical supply chain gap for the U.S. defense industry since the equipment supply chain used to support conventional hybridization processes is shrnking rapidly and is non U.S. based. Apart from the technical and supply chain benefits, the disruptive hybridization process brings significant cost advantages to the manufacture of imaging focal plane arrays.