A semiconductor device comprises a semiconductor element having electrodes and metal bumps are attached to the electrodes. The metal bumps include copper cores and gold surface layers covering the cores. In addition, the metal bumps may include gold bump elements and solder bump elements connected together.
An interconnection structure includes an electrically conductive bump, wherein the electrically conductive bump has a metal body having a distal end. The metal body is free of solder. An outermost layer of diffusion solder is positioned on at least regions of the metal body of the electrically conductive bump.
