Electrical characteristics of silicon-nodule-related via failures observedin aluminum-silicon interconnects

We have evaluated the electrical characteristics of silicon-nodule-related via failures in the aluminum interconnects of silicon integrated circuits. Current-voltage measurements indicated that the conduction mechanism follow s Ohm's law. The resistance was 1.5-3 k Omega for a silicon nodule at a via of 1.0 mu m x 1.0 mu m. When the applied voltage was 3-6 V, the resistance decreased abruptly. This transition (abrupt decrease in resistance) was ir reversible. We think that the resistance of 1.5-3 k Omega and the transitio n voltage of 3-6 V are two factors characterizing the silicon nodule. We ca n explain these values by assuming that aluminum in the silicon nodules at a solubility limit concentration acts as an acceptor.