Effects of high current pulses on integrated circuit metallization reliability

Transient heat flow analysis using two-dimensional finite-element method has been used to calculate the temperature rise of aluminum lines on passivated and unpassivated silicon substrates. The results are used to predict the effect of self-heating on the electromigration lifetime of aluminum interconnects under pulse current stressing. A model has been developed to incorporate damage relaxation and self-heating effects on electromigration. It is shown that self-heating is expected to produce less than 20% error in typical accelerated testing conditions provided the peak current density (J/sub p/) is less than 4*10/sup 6/ A/cm/sup 2/. Design rules based on keeping the average current density (J/sub av/) constant are acceptable provided that duty factor is larger than 1% for all frequencies above 1 MHz.<
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