Electroless fabrication of super uniform nickel bumps on the TFT driver substrates for micro-LED display

This study aims to achieve high-yield micro-LED chip bonding and thus further advance the innovation of micro-LED interconnection technology. In this research, an electroless plating method was used to achieve the highly uniform nickel bump arrays on a thin-film transistor (TFT) driver substrate. Initially, the photoresists AZ4620 and AZ2070 are chosen for the experiments, which can cover the step structure uniformly of TFT substrate. Subsequently, the shape of bumps on the TFT substrate influenced by the plasma treatment and the deposition time was investigated. The result indicated that microbump arrays with a uniformity of less than 1% could be successfully fabricated by employing a 5-min plasma treatment and incorporating surfactant additions at concentrations of 0.02%, and the process of preparation has a high repeatability, which lays a solid foundation for the subsequent electroless plating bonding, and provides a critical reference for the breakthrough of micro-LED interconnection key technology.