Design and characterization of a novel low temperature wafer level bonding technology

A wafer level bonding technology based on Cu-Sn-In ternary material system was investigated to realize low temperature 3D interconnections. The bonding process was dedicated designed and optimized. Experiments with different bonding temperature was conducted and compared and the lowest bonding temperature was 170 degrees C. The microstructure analysis indicated that bonding interface at 170 degrees C was composed of Cu/Cu-6(Sn,In)s/Cu and with temperature increasing, Cu-3(Sn,In)s phase would take form. The results of shear strength, pull test, electrical resistance and thermal cycling reliability test manifested that the bonding structure have sufficient bonding strength, good conductivity, and reliability for application.