Using Hybrid Bonding for Stacked Bi-Color Micro-Light-Emitting Diodes

In this work, a vertically stacked bi-color micro-light-emitting diode (Micro-LED) array structure employing Au–Sn hybrid bonding technology is presented. The design integrates blue flip-chip and green vertical Micro-LEDs into a common cathode circuit configuration, achieving an ultrafine pixel pitch of $5~\mu $ m across $343\times 387$ array on 1.6-cm² substrate. Precise hybrid bonding was performed at $233~^{\circ }$ C for 30 min, enabling effective Au–Sn alloy formation. The structure’s performance was verified through electrical character and cross-sectional SEM-EDX analysis, demonstrating minimal voltage increase postbonding and confirming the feasibility of independent control for both colors. This integration approach provides a scalable solution for high resolution, compact, and low-power consumption. The Micro-LEDs display applications, particularly suited for near-eye devices such as augmented and virtual reality systems.