Capillary Self-Alignment Assisted Hybrid Robotic Handling for Ultra-Thin Die Stacking

Ultra-thin dies are difficult to package because of their fragility and flexibility. Current ultra-thin die integration technology for 3D microsystems relies on robotic pick-andplace machines and machine vision, which has rather limited throughput for high-accuracy assembly of fragile ultra-thin dies. In this paper, we report a hybrid assembly strategy that consists of robotic pick-and-place using a vacuum micro-gripper, and droplet self-alignment by capillary force. Ultrathin dies with breakable links are chosen as part of the assembly strategy. Experimental results show that we can align ultra-thin (10 mu m) dies with sub-micron accuracy without machine vision. A fully automatic sequence of stacking several of these dies is demonstrated. Up to 12 ultra-thin dies have been stacked. These early results show that die-to-die integration of ultra-thin dies with higher throughput than the current industry robot is possible by applying both robotic handling and droplet self-alignment to ultra-thin die assembly.