A Novel Layer Structural Design for Silver-indium Transient Liquid Phase Bonding Technology by Introducing a Diffusion Barrier

Silver-indium transient liquid phase bonding (Ag-In TLP), as an interconnect technology, offers low bonding temperature, short bonding time, and high reliability, making it widely applicable for packaging electronic devices such as power devices and optoelectronic devices. In previous studies, the Ag-In bonding joints often contained voids due to excessive diffusion of indium into silver. In this research, a diffusion barrier layer between silver and indium was introduced to reduce pre-bonding diffusion, ultimately resulting in a low-porosity bonding interface. Electron beam evaporation (E-beam) and electroplating were primarily used to deposit Ag and In, and joints were obtained through flip-chip bonding processes. The bonding interface quality with diffusion barrier and without diffusion barrier have been carefully examined with SEM imaging, whereby directly demonstrating the functionality of the designed diffusion barrier. Moreover, the interfacial microstructure and element distribution of the Ag-In transient liquid phase bonding were also discussed through energy dispersive spectroscopy analysis. Through the above analysis, we found that introducing a diffusion barrier layer into the Ag-In transient liquid phase bonding process can effectively improve the quality of the bonding interface.