EFFECT OF MICROSTRUCTURE ON ELECTROMIGRATION KINETICS IN CU LINES

Strong correlation of the modes of electromigration damage and microst ructure is reported for Cu films. It is found that changes in the micr ostructure lead to qualitative variation in electromigration damage ki netics--from the traditional open circuit due to void growth across th e line, to damage growing along the line, and not leading to failure. Some of our findings are consistent with the theoretical model based o n interplay between surface and grain boundary diffusion. The activati on energy E-a = 0.95 eV of electromigration mass transport was measure d using a modified electrical resistance method.