EFFECT OF APPLIED MECHANICAL-STRESS ON THE ELECTROMIGRATION FAILURE TIMES OF ALUMINUM INTERCONNECTS

Accelerated lifetime electromigration tests were performed on pure aluminum interconnect lines which were subjected to an applied mechanical bending stress. The median time to open failure (MTTF) was found to decrease with increasing applied tensile stress. The diminished failure times suggest a decrease in the activation energy for aluminum grain boundary self-diffusion on the order of 0.003 eV per 100 MPa of applied stress, resulting in a MTTF reduction of 10% at 210-degrees-C for an increase in tensile stress of 100 MPa.