PULSED-CURRENT DUTY CYCLE DEPENDENCE OF ELECTROMIGRATION-INDUCED STRESS GENERATION IN ALUMINUM CONDUCTORS

The effect of duty cycle of pulsed de currents on the critical length- current density product, (jl(c)), was measured using the Blech-Kinsbro n edge-displacement technique [Thin Solid Films 25, 327, (1975)], Unen capsulated Al edge-displacement segments were stressed at various duty cycles and the critical lengths, the so-called ''Blech lengths,'' wer e measured, it was found that jl(c) increased with decreasing duty cyc le, We measured a factor of 2.6 increase in jl(c) for the 25% duty cyc le as compared to de. This duty cycle dependence of Blech length impli es that electromigration resistance for an integrated circuit would be increased for small duty cycle operation by increasing the fraction o f interconnects which are sub-Blech-length and are not susceptible to EM damage.