Reliability of metal interconnect after a high-current pulse

In certain situations, very large scale integration (VLSI) metal interconnects are subjected to short duration high current pulses. This occurs in FPGA programming, and in radiation testing for latchup. The authors have determined the effects of such pulsing on the long term reliability of Al (1% Cu) metallization with W cladding on top and bottom. The reliabilities of pulsed and unpulsed lines were established using accelerated electromigration testing. Lines pulsed below the immediate catastrophic threshold were seen to have slightly improved electromigration lifetimes, but as the failure threshold is approached, electromigration lifetime decreases abruptly. Therefore, high current pulsing provides no reliability hazard in this metallization system below catastrophic threshold.