Direct Transfer-Bonding Approach toward High-Yield, Large-Area Micro Light-Emitting Diode Integration

Abstract

Conventional mass-transfer techniques for micro-LED display fabrication typically involve at least three sequential transfer steps to integrate micro-LED chips into the final driving circuitry. However, as chip sizes continue to decrease, the risk of mechanical damage during each transfer step increases─making even a single transfer step potentially detrimental to device integrity. To overcome this limitation, we introduce a direct transfer-bonding approach that eliminates the need for temporary substrates and intermediate transfer stages. Our strategy simplifies processing, enhances yield, and reduces manufacturing costs. Through experimental validation and finite element analysis, we developed an optimized transfer architecture for laser lift-off conditions and bump structures. Under optimal parameters─a bump height of 6 μm and 30% laser power─the process achieved a maximum transfer yield of 94.3%, demonstrating the feasibility of high-precision and high-reliability integration. This strategy offers a scalable and cost-effective solution for the mass production of micro-LED displays.