Micro-Scale System Integration Via Molten-Alloy Driven Self-Assembly and Scaling of Metal Interconnects

Self-assembly, or the spontaneous organization of parts into larger structures via energy minimization, is an attractive solution to overcome packaging and integration challenges. Capillary forces from a molten alloy constitute one self-assembly method, but little is known about reducing molten alloy contact size while maintaining proper function. We address these issues using a eutectic Bi-Sn alloy, and overcome corrosion problems by selecting the right fluid environment. We demonstrate the self-assembly of 100 mum and 40 mum sized parts on templates, with yields of 97% and 85%, respectively. Yields were lower with 20 mum parts, suggesting a lower limit for this particular system.