Backend dielectric breakdown dependence on linewidth and pattern density

Time-dependent dielectric breakdown of copper/low-k interconnects has been found to degrade for narrow metal lines. Several feasible causes for degradation have been investigated, including enhanced electric fields, the optical proximity effect, and microloading in etch. Microloading is found to be the best explanation of the observed behavior. A mathematical model has been developed to relate the geometries of layout features to mean-time-to-failure (MTTF).