Failure Mechanisms in Integrated Circuit Interconnect Systems

Failure mechanism in interconnect systems employed in semiconductor devices have been reviewed and analyzed in some detail1 from the early purple plague producing aluminum-gold system to the latest platinum-titanium-gold beam lead process. It is shown that intermetallic compound formation occurs in all the systems studied. In the aluminum-gold system, the formation of the purple plague compound and other intermetallics is catalyzed by the presence of silicon, causing rapid degradation of bond strength. The compound formation up over the oxide is accompanied by void formation as a result of Kirkendall effect, leading to mechanically open bonds. Compound formation is found or may be expected in all the interconnect systems analyzed. The only interconnect system free of these problems is the all aluminum system.