The performance of electroplated damascene material was investigated by performing drift experiments on Blech-type test structures having polycrystalline or bamboo microstructures. In the former case, micro-texture data were also obtained from electron back-scattering diffraction. Whereas both the bonding areas and 10μm-wide lines were found to have predominantly random grain orientations, drift studies indicated the importance of strongly segregating impurities in controlling Cu grain-boundary electromigration. In the case of bamboo lines, the effect of various barrier layers (Ta, TaN, TiN) was investigated. Drift was shown to proceed at the Cu/barrier interface in all cases, but was faster for Ta; as compared with TaN or TiN.

Microtexture and Electromigration-Induced Drift in Electroplated Damascene Cu. J.Proost, T.Hirato, T.Furuhara, K.Maex, J.P.Celis: Journal of Applied Physics, 2000, 87[6], 2792-802