Through Si vias using liquid metal conductors for re-workable 3D electronics

This paper describes the design and fabrication of liquid metal interconnects (vias) for 2.5D and 3D integration. The liquid metal is gallium indium eutectic (78.6% Ga, 21.4% In) with a melting temperature of approximately 15.7 °C, which is introduced into via openings of a silicon interposer. This liquid metal interconnect technology can be integrated with existing interposer technologies, including capacitors and traditional (solid metal) through-silicon vias (TSVs). We anticipate that liquid metal interconnects can better accommodate thermal stresses and provide re-workability in case of chip failure or upgrade. We determined the liquid metal resistance to be 1.67 KΩ at room temperature and observed an increase in the resistance to 5.6 KΩ at 37°C.