High melting point soldering layer alloyed by transient liquid phase and fabrication method for the same, and semiconductor device

A high melting point soldering layer includes a low melting point metal layer, a first high melting point metal layer disposed on a surface of the low melting point metal layer, and a second high melting point metal layer disposed at a back side of the low melting point metal layer. The low melting point metal layer, the first high melting point metal layer, and the second high melting point metal layer are mutually alloyed by transient liquid phase bonding, by annealing not less than a melting temperature of the low melting point metal layer, diffusing the metal of the low melting point metal layer into an alloy of the first high melting point metal layer and the second high melting point metal layer. The high melting point soldering layer has a higher melting point temperature than that of the low melting point metal layer. It provides a binary based high melting point soldering layer having TLP bonding of a high melting point according to a low temperature processing. A fabrication method for the high melting point soldering layer and a semiconductor device to which the high melting point soldering layer is applied