A fatigue-free silicon device structure

Germanium devices, when correctly used, are capable of essentially infinite life. It was commonly assumed in early higher temperature semiconductor work that silicon devices and those of materials, such as silicon carbide and III-V compounds would have similar life expectancy. That this is not realized in soft-soldered silicon devices is now well established. Evidence is presented to show that this limitation in life is due to fatigue rupture of the soft-soldered joints when they are subjected to cyclic thermal stress. A new hard-soldered structure is described which has been proved by long experience to eliminate fatigue failure completely.