Direct laser transfer and thermocompression bonding process of blue GaN micro-LED arrays

Abstract

Large-scale production of micro-LED displays encounters significant technical challenges, particularly in the mass transfer process of micro-LEDs. This study innovatively explores the direct laser transfer process of blue GaN micro-LED arrays utilizing rubber tape as the receiving material, which essentially involves a selective laser liftoff technique to transfer micro-LEDs directly from their growth substrate to the target substrate. The coherent UV transfer system with a laser wavelength of 248 nm was used in this Letter. Notably, a 30 × 15 micro-LED array, including the word “SHU,” was transferred and displayed. The micro-LEDs were interconnected to the substrate through thermocompression bonding. A comparative analysis of the photoelectric properties of the micro-LEDs before and after transfer was conducted, and the shear force after bonding was analyzed. The experimental results demonstrate that this direct laser transfer technique achieves high yield and precise transfer of micro-LEDs with little impact on their photoelectric and mechanical performance, exhibiting excellent display characteristics. This study provides valuable insights for advancing the further development and commercialization of micro-LED technology.