Very high current density package level electromigration test for copper interconnects

In this paper, we present quantitative analyses of the impact of Joule heating on the package level electromigration (EM) test of copper dual damascene (DD) interconnects with linewidths of 0.28 and 0.7 μm. A total of 120 samples are tested with a maximum current density of 8 MA/cm². It is found that high test current density has a negligible impact on the estimation of activation energy and offers an opportunity to shorten the test time. However, the current density exponent is found to be a strong function of test current density, especially for interconnects with a larger linewidth. Correction due to Joule heating on the estimation of the current density exponent is described.