Realizing a residue-free polymer based ultrahigh yield laser transfer of Micro-LED display pixels using data grouping and empirical relationship

Abstract

This paper presents an ultra-high yield Micro-LED pixel transfer method without residual polymer. The approach is based on a laser transfer scheme, combined with data grouping and an empirical relationship. These strategies effectively address the fundamental yield challenges in Micro-LEDs, which arise from the difficulty of transferring a large number of devices. Initially, we identified the issues of chip damage and missing during the laser transfer process and analyzed the underlying causes by the preparation process. Subsequently, the optimal process conditions were determined. An empirical relationship was also established. In addition, the effects of laser energy, laser spot size, and chip subsidence depth on Micro-LED stripping and transfer performance were analyzed. The results indicate that the chip retention rate is at its highest when the energy density of the controlled laser lift-off is within the range of 1200-1500mJ/cm². Additionally, the secondary transfer yield was 100 % when the energy density of the laser transfer and the depth of the chip subsidence satisfied empirical relationship, and the laser spot size was 30 μm × 38 μm. The preparatory process is highly reproducible and provides a robust foundation for subsequent laser transfer. Furthermore, it offers a significant reference for advancing the critical technologies involved in Micro-LED mass production.