Au/Al Wire Bond Interface Resistance Degradation Rate Simulations

Gold wires are often used to connect aluminum terminals on semiconductor chips for signal transmission. Au-Al bonds degrade over time with temperature due to formation of intermetallic compounds at the gold-aluminum interface. A literature overview of the research on the Au-Al intermetallic compounds is outlined. Formation of these intermetallic compounds is governed by diffusion rules; however, the observed interface failure rates do not always follow the expected Fickian t
^1/2
time dependence. Gold-aluminum intermetallic compounds in turn cause Kirkendall voiding. The proliferation of Kirkendall voids over time separates the two interfaces. A literature overview of research on Kirkendall voiding is also outlined. In this paper, time-dependence generated by simulations of the Au/Al interface degradation due to Kirkendall voids is compared with the observed data time-dependence and the empirical failure rate time-dependences and their diverse rates of progression.