Research on Hybrid Bonding Process of Micro-LED Preparation Based on Asymmetric Structure

In this letter, we propose a hybrid bonding process for the preparation of micro-light-emitting diode (Micro-LED) based on asymmetric structures. This process employs a bonding system comprised of metal and photopolymer. The asymmetric structure is formed by utilizing a blue film to selectively remove the metal from the photoresist after the metal has been evaporated. Cross-sectional observation of the Micro-LED after bonding reveals that effective filling can be achieved. Consequently, compared to the symmetrical structure process, the steps of spin coating the polymer and chemical mechanical polishing (CMP) on both sides are omitted, greatly simplifying the process. Tests indicate that the Micro-LED device manufactured using this method exhibits excellent electrical and optical properties, with a bonding strength of 17.1 MPa, which is 73.6% greater than that of bump bonding. Furthermore, the asymmetric structure mitigates the sliding issues associated with joining symmetric structures and enhances pixel isolation, thereby improving bonding accuracy. It is crucial for increasing the yield and reducing the cost of Micro-LED in terms of commercialization.