Hybrid Heterogeneous Imaging Arrays with Reinforced Functionality and Reliability

Hybridization of heterogeneous components using flip chip technology is a key process for the assembly of large focal plane array (FPA) used in imaging systems. Since these systems are usually submitted to large thermal excursion, even in normal operation, substantial stress is induced in the interconnection layer, especially near the edge of the FPA. Such stress can result in cracks or delamination and jeopardize reliability. This work describes an innovative device and its associated process "AMIS" (stands for French AMinci, ISole) that: (a) decreases stress induced in the interconnection bumps. (b) Reduces serial access resistance to the pixel. (c) Reduces optical cross coupling between pixels. In this study, we demonstrate the feasibility of such hybrid heterogeneous systems and evaluate their mechanical robustness when submitted to severe thermal cycling.