Microstructure and electromigration in copper damascene lines

Grain sizes and crystallographic orientations of Cu were analyzed versus li newidth in damascene Cu interconnects. Pure bamboo lines were not obtained because grain size decreased as linewidth was reduced. Comparison of electr omigration results, for wide line Chemical vapor deposition-Cu (3 mu m) pol ycrystalline structure, and narrow lines (0.5 mu m) quasi-bamboo structure, provided almost the same activation energy E(a)similar to 0.65 eV. even th ough the poor (2 0 0) texture has rotated in the film plane for the narrow damascene lines. These results are in agreement with copper diffusion invol ving surface diffusion. Besides. even with a polycrystalline crystallograph ic orientation, PVD-Cu samples showed a better activation energy value E-a= 1.02 eV. (C) 2000 Elsevier Science Ltd. All rights reserved.