MICROSTRUCTURE BASED STATISTICAL-MODEL OF ELECTROMIGRATION DAMAGE IN CONFINED LINE METALLIZATIONS IN THE PRESENCE OF THERMALLY-INDUCED STRESSES

Probability distributions are evaluated for electromigration induced o pen failures in narrow, passivated interconnects with a near-bamboo gr ain structure. Void formation is initiated at the cathode ends of the polycrystalline line segments or ''grain clusters.'' If these clusters are longer than a critical size L(c), they can accommodate enough ato ms for voids to reach the critical size to fail the line. Obviously, t he critical size L(c) depends on the thermal stress: a cluster under a tensile stress is able to incorporate more atoms from the void than a n unstressed cluster. In the case the clusters are shorter than L(c), atoms from the voids must be distributed also to bamboo sections, outs ide the clusters, in order for the voids to induce open failures. Base d on this physical picture, failure probabilities are evaluated as a f unction of time. The predicted failure distributions and parametric de pendencies compare well with the experiments.