Laser Lift Off and Multi Dies Collective Bonding for Inorganic $\mu \text{LED}$ with the Newly Developed Material

Abstract

In this work, the temporally fixing carrier for the laser lift off (LLO) and the bonding strength leveling film (BFL) was developed to improve the productivity of a series of the process, LLO, mass transfer and collective bonding of $\mu\text{LEDs}$ . The $\mu\text{LEDs}$ on the sapphire carrier went through the LLO process with the developed carrier, and temporally mounting process with prepared pickup tool to the final target substrate laminated with nonconductive film. As a results, the total yield of mass transfer was > 99%. After the transfer process, 4,465 $\mu\text{LEDs}$ in $3.3 \text{mm}\times 2.8 \text{mm}$ , were integrated to the substrate by collective bonding with BFL film which can apply uniform pressure and temperature among $\mu\text{LEDs}$ in the process. The cross sectional image after the bonding showed that the pad of $\mu\text{LEDs}$ and the target substrate form the uniform connect.