The Full-IMCs Interconnects through Transient Liquid Phase Bonding of Ga/Cu System for Advanced Electronic Packaging

To meet the needs for further miniaturization and multi-functionalization of microelectronics, three-dimensional (3D) integrated circuits and advanced interconnects have become the most promising packaging technology in the semiconductor industry. 3D integrated circuit (ICs) packaging is based on 2D processes and stacks of ICs vertically to achieve the dual role of space compression and improving data transmission efficiency. As a relatively new bonding method, the low temperature transient liquid phase bonding (TLPB) technique shows a great potential for multiple bonding on the same substrate. This study uses gallium (Ga) metal as the interconnect material to achieve the Cu-to-Cu TLPB process. The aim is to investigate the Ga/Cu IMCs grains growth kinetics, the microstructure of IMCs in these joints and their mechanical properties bonded at 200°C. The results show that the Ga solder presents excellent bondability on Cu substrate, forming cube-like CuGa2 grains which can grow stably at 200°C, and this anisotropy of IMC grains growth is beneficial to the microstructure and strength of the joint. These results provide strong evidence for the feasibility of such a novel manufacturing route for 3D IC packaging and heterogeneous integration.