Effect of metal liner on electromigration in Cu Damascene lines

Abstract

Electromigration in Cu single Damascene lines capped with amorphous a-Si Cx Ny Hz and fabricated with various Ta-based liners is investigated. The Ta-based liner layers were deposited using atomic layer and physical vapor deposition techniques. The crystallographic phases of the Ta liners were determined using x-ray and transmission electron diffraction. Although the Cu electromigration lifetimes are determined by % resistance increase failure criteria that are dependent on the liner resistance, the Cu void growth rate was found to be insensitive to the phases of Ta. This result is consistent with the dominant diffusion path being along the Cua-Si Cx Ny Hz interface in these samples. The activation energy for Cu along Cua-Si Cx Ny Hz interface diffusion was found to be 1.0±0.04 eV. © 2005 American Institute of Physics.