Hybridization Techniques for Ultra-Small Pitch Focal Plane Arrays

ABSTRACT:To address the need for a low-cost, high-pixel-density focal plane array (FPA) hybridization process, a nanotechnology-based metal interconnect and bonding approach will be refined. The process is compatible with wafer-to-wafer, chip-to-wafer, and chip-to-chip processing, requires only modest capital investment, and can be performed with high yields at less cost and finer pitch compared to todays indium bump hybridization technologies. The process uses a combination of nanoparticle metal inks, inkjet-print deposition, and nanoimprint lithography technologies. In Phase I, the process was shown to achieve better than 4 micron pixel pitch electrical interconnects. In Phase II, a variety of metal nanoparticle inks, including gold, silver, tin, zinc, etc., will be developed and shown to be capable of being printed or otherwise solution-deposited into two-dimensional and three-dimensional electrical conductors. A process using inkjet deposition and nanolithography will be used to demonstrate reliable interconnects, over large areas on a better than five-micron pixel pitch. The reliability of the technique will be verified using Si-Si and Si-compound-semiconductor (InSb, InGaAs, HgCdTe, etc.) test vehicles. Finite element analysis will be used to complete a failure modes effects and analysis (FMEA) effort, which will be the basis for a reliability growth program.BENEFIT:The technologies will be made available to the market through licensing agreements, hybridization equipment sales, and metal, dielectric, and optical ink sales. The technology is scalable to submicron pixels, making it a solution to fabricate imagers in consumer cell phone cameras, surveillance cameras, and infrared focal plane arrays, as well high-density, low-footprint 2.5 electronics packages, and 3D stacked integrated circuits. The technology also lends itself to flexible and printed electronics and fully integrated additive manufactured assemblies.