Hybrid Bonding Process for Fabricating Micro-LED Based on the Au–In/Nonphotosensitive PI System

With the introduction of the Micro-LED concept, numerous researchers have conducted extensive studies on Micro-LED chip structures, the mitigation of sidewall damage caused by etching, and the design of driving circuits, achieving remarkable results. However, as the pixel size of Micro-LED continues to decrease, challenges in chip-level bonding integration have emerged. In this article, we present a hybrid bonding process for the fabrication of Micro-LED using the AuIn/nonphotosensitive polyimide (PI) system. This process uses photoresist as a mask to etch the polymer dielectric layer, followed by electron beam evaporation and lift-off techniques to create an analog substrate with an asymmetric structure. This asymmetric design not only mitigates slippage issues associated with symmetric structures during bonding, thereby improving alignment accuracy, but also enhances electrical isolation between pixels. The fabricated blue Micro-LED device exhibits a turn-on voltage (VT) of 2.3 V, a luminance of 63 135.28 cd/m² at 5 V, a bonding yield of 99.97%, and an 88.7% improvement in bonding strength compared with bump bonding device. For Micro-LED display technology to advance toward commercialization, high yield, in addition to outstanding optoelectronic performance, is an essential requirement. This process demonstrates significant application potential in the commercial production of high-yield, high-resolution Micro-LED.