A study of purple plague and its role in integrated circuits

Purple plague is shown to be the development of a purple intermetallic compound AuAl2when gold wires are bonded to aluminum metallization regions in silicon transistors and integrated circuits. It is further shown that the rate of formation of purple plague is catalyzed by the presence and interaction of silicon, and that the catalyzed product is harmful to the device. Part of the ternary system is investigated to elucidate the mechanism of the ternary interaction. Various metallization-wire systems are reviewed which are currently in use or development. The use of aluminum wire to aluminum metallization is shown to be the simplest, most reliable method presently available for eliminating purple plague.