High‐current failure levels of TaSi2–polycide/Al‐alloy bilevel‐conductor composites were measured using 10 min increment step‐stress tests. Al‐alloy metallizations were Al and Al–1%Si; polycide and metal linewidths ranged from 2.5 to 3.0 μm; and interlevel‐contact sizes ranged from 1.5 to 2.0 μm2. In all cases, the weak links in the bilevel composite were the interlevel contacts. In units with contact resistances less than 1 Ω, failures occurred at the positive contact at polycide‐line current densities ≥1.4×107A/cm2, which resulted in Joule heating of the polycide line to ≥400 °C. Polycide line damage and Al, which had migrated in the direction of the electric field, often extended to distances>100 μm from the failed contact. Early failures, highly localized at the negative contact, were consistently experienced by units with initial contact resistances above approximately 1 Ω. The failure levels decreased (to current densities as low as 5×106A/cm2) with increasing initial contact resistance. Thirty cycles of thermal shock (−70 to +100 °C) resulted in no reduction in the current level at which high‐current failure occurred in units with good contacts.