High temperature investigation on a nickel-tin transient liquid-phase wafer bonding up to 600 °C

This paper reports on the capability of a nickel–tin (Ni–Sn) bond solder to be stable at high temperature application up to 600 °C. The Ni–Sn bond solder is fabricated using a transient liquid phase method of a 6′′ wafer-level bonding technique. The capability is determined by investigating the phase change of Ni–Sn compounds, which are grown within the bond solder, as well as the mechanical and electrical stability of the bond solder before and after annealing (in vacuum at 600 °C for 24 h). After annealing, the Ni–Sn phase has transformed to a new Ni–Sn phase with a higher re-melting temperature. A shear test has determined that the bond solder exhibits a relatively high bond strength before and after annealing. Using a daisy chain structure, the electrical resistance of the bond solder is determined and encounters a tolerable increase after annealing. Re-melting of the bond solder has not occurred during annealing. The daisy chain structure can be adapted for creating a bond solder which has a dense microstructure