Abstract
Electromigration (EM) in copper dual-damascene interconnects with extensions(also described as overhang regions or reservoirs) in the upper metal (M2) were investigated. It was found that as the extension length increases from 0 to 60 nm, the median-time-to-failure increased from 50 to 140 h, representing a ∼200% improvement in lifetimes. However, further increment of the extension length from 60 to 120 nm did not result in any significant improvement in EM lifetimes. Based on calculations of current densities in the reservoir regions and recently reported nucleation, void movement, and agglomeration-based EM phenomena, it is proposed that there is a critical extension length beyond which increasing extension lengths will not lead to longer EM lifetimes.
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References
C.K. Hu, R. Rosenberg, and K.L. Lee: Electromigration path in Cu thin-film lines. Appl. Phys. Lett. 74, 2945 (1999).
J.R. Lloyd and J.J. Clement: Electromigration in copper conductors. Thin Solid Films 262, 135 (1995).
C.K. Hu, L. Gignac, R. Rosenberg, E. Liniger, J. Rubino, C. Sambucetti, A. Domenicucci, X. Chen, and A.K. Stamper: Reduced electromigration of Cu wires by surface coating. Appl. Phys. Lett. 81, 1782 (2002).
C.K. Hu, L. Gignac, E. Liniger, B. Herbst, D.L. Rath, S.T. Chen, S. Kaldor, A. Simon, and W.T. Tseng: Comparison of Cu electromigration lifetime in Cu interconnects coated with various caps. Appl. Phys. Lett. 83, 869 (2003).
Y. Shacham-Diamand and S. Lopatin: High aspect ratio quarter-micron electroless copper integrated technology: Invited lecture. Microelectron. Eng. 37–38, 77 (1997).
A. von Glasow, A.H. Fischer, D. Bunel, G. Friese, A. Hausmann, O. Heitzsch, M. Hommel, J. Kriz, S. Penka, P. Raffin, C. Robin, H.P. Sperlich, F. Ungar, and A.E. Zitzelsberger: The influence of the SiN cap process on the electromigration and stressvoiding performance of dual damascene Cu interconnects in Proc. 41st Annual Int. Rel. Phy. Symp. (IEEE, Piscataway, NJ, 2003), p. 146.
K.N. Tu, C.C. Yeh, C.Y. Liu, and C. Chen: Effect of current crowding on vacancy diffusion and void formation in electromigration. Appl. Phys. Lett. 76, 988 (2000).
Y.B. Park and I.S. Jeon: Effects of mechanical stress at no current stressed area on electromigration reliability of multilevel interconnects. Microelectron. Eng. 71, 76 (2004).
I.S. Jeon and Y.B. Park: Analysis of the reservoir effect on electromigration reliability. Microelectron. Reliab. 44, 917 (2004).
A.V. Vairagar, S.G. Mhaisalkar, A. Krishnamoorthy, K.N. Tu, A.M. Gusak, M.A. Meyer, and E. Zschech: In situ observation of electromigration-induced void migration in dual-damascene Cu interconnect structures. Appl. Phys. Lett. 85, 2502 (2004).
C.L. Gan, C.V. Thompson, K.L. Pey, W.K. Chio, H.L. Tay, B. Yu, and M.K. Radhakrishnan: Effect of current direction on the lifetime of different levels of Cu dual-damascene metallization. Appl. Phys. Lett. 79, 4592 (2001).
R.G. Filippi, G.A. Biery, and R.A. Wachnik: The electromigration short-length effect in Ti–AlCu–Ti metallization with tungsten studs. J. Appl. Phys. 78, 3756 (1995).
P.S. Ho: Motion of inclusion induced by a direct current and a temperature gradient. J. Appl. Phys. 41, 64 (1970).
V.P. Zhdanov: Elementary Physicochemical Processes on Solid Surfaces, (Plenum Press, New York, 1991), p. 52.
M.C. Gutzwiller: Dislocations and elections in metals, in Atomic and Electronic Structure of Metals, edited by J.J. Gilman and W.A. Tiller (ASM, Metals Park, OH, 1966), p. 231.
R.O. Simmons and R.W. Balluffi: Measurement of equilibrium concentrations of vacancies in copper. Phys. Rev. 129, 1533 (1963).
A.V. Vairagar, S.G. Mhaisalkar, A. Krishnamoorthy, M.A. Meyer, E. Zschech, K.N. Tu, and A.M. Gusak: Direct evidence of electromigration failure mechanism in dual-damascene Cu interconnect tree structures. Appl. Phys. Lett. 87, 081909 (2005).
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Gan, Z.H., Shao, W., Mhaisalkar, S.G. et al. Reservoir effect and the role of low current density regions on electromigration lifetimes in copper interconnects. Journal of Materials Research 21, 2241–2245 (2006). https://doi.org/10.1557/jmr.2006.0270
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DOI: https://doi.org/10.1557/jmr.2006.0270