Anelasticity study on electromigration effect in Cu thin films

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 442; no. 1; pp. 342 - 346
• Main Authors: Mizubayashi, H., Goto, K., Ebisawa, T., Tanimoto, H.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 20.12.2006; Elsevier
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cu interconnects; Electromigration; Exact sciences and technology; Internal friction; Other nonelectronic physical properties; Physical properties of thin films, nonelectronic; Physics; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Young's modulus; Electromigration; Cu interconnects; Young's modulus; Internal friction; Annealing; Electrical conductivity; Sandwich structures; Thin films; Young modulus; Tantalum; Anelasticity; Electrodiffusion; Transport processes; Copper; Current density; Activation energy
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2006.02.227

Electromigration (EM) tests on Cu thin film circuits below or near 373 K with the current density between 1 × 10 9 A/m 2 and 8 × 10 9 A/m 2 were carried out by means of the composite vibrating reed method. The resonant frequency ( f) and the internal friction ( Q −1) of the composite reed and the resistivity ( R) of the thin film circuit were measured during isothermal EM tests for as deposited Cu/Ta films, Cu/Ta films annealed at 450 K and as deposited Ta/Cu/Ta films. An increase in f, a decrease in Q −1 and a decrease in R were commonly observed. The activation energies found for the EM process ( E EM) range between 0.21 and 0.41 eV for the as deposited Cu/Ta films, between 0.21 and 0.59 eV for the annealed Cu/Ta films and around 0.3 eV for as deposited Ta/Cu/Ta films. It is suggested that a previously unrecognized mass transport process with low E EM operates in these Cu thin films.