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 in this work. The design integrates blue flip-chip and green vertical Micro-LEDs into a common cathode circuit configuration, achieving an ultra-fine pixel pitch of 5 μm across a 343 × 387 array on a 1.6 cm² substrate. Precise hybrid bonding was performed at 233°C for 30 minutes, 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 post-bonding 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 Micro-LEDs display applications, particularly suited for near-eye devices such as augmented and virtual reality systems.