Hostname: page-component-586b7cd67f-dsjbd Total loading time: 0 Render date: 2024-11-26T11:06:23.642Z Has data issue: false hasContentIssue false
  • English
  • Français

Reservoir effect and the role of low current density regions on electromigration lifetimes in copper interconnects

Published online by Cambridge University Press:  03 March 2011

Z.H. Gan ,
W. Shao ,
S.G. Mhaisalkar ,
Z. Chen ,
Hongyu Li ,
K.N. Tu  and
A.M. Gusak
Z.H. Gan*
Affiliation:
School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798
W. Shao
Affiliation:
School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798
S.G. Mhaisalkar
Affiliation:
School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798
Z. Chen
Affiliation:
School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798
Hongyu Li
Affiliation:
Institute of Microelectronics, Singapore 117685
K.N. Tu
Affiliation:
Department of Materials Science and Engineering, University of California—Los Angeles, Los Angeles, California 90095-1595
A.M. Gusak
Affiliation:
Cherkasy National University, Cherkasy 18017, Ukraine
*
a) Address all correspondence to this author. e-mail: [email protected]
Get access

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.

Keywords

CuElectromigrationScanning electron microscopy (SEM)
Type
Articles
Information
Journal of Materials Research , Volume 21 , Issue 9 , September 2006 , pp. 2241 - 2245
Copyright
Copyright © Materials Research Society 2006

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1Hu, C.K., Rosenberg, R., and Lee, K.L.: Electromigration path in Cu thin-film lines. Appl. Phys. Lett. 74, 2945 (1999).CrossRefGoogle Scholar
2Lloyd, J.R. and Clement, J.J.: Electromigration in copper conductors. Thin Solid Films 262, 135 (1995).CrossRefGoogle Scholar
3Hu, C.K., Gignac, L., Rosenberg, R., Liniger, E., Rubino, J., Sambucetti, C., Domenicucci, A., Chen, X., and Stamper, A.K.: Reduced electromigration of Cu wires by surface coating. Appl. Phys. Lett. 81, 1782 (2002).Google Scholar
4Hu, C.K., Gignac, L., Liniger, E., Herbst, B., Rath, D.L., Chen, S.T., Kaldor, S., Simon, A., and Tseng, W.T.: Comparison of Cu electromigration lifetime in Cu interconnects coated with various caps. Appl. Phys. Lett. 83, 869 (2003).CrossRefGoogle Scholar
5Shacham-Diamand, Y. and Lopatin, S.: High aspect ratio quarter-micron electroless copper integrated technology: Invited lecture. Microelectron. Eng. 37–38, 77 (1997).CrossRefGoogle Scholar
6von Glasow, A., Fischer, A.H., Bunel, D., Friese, G., Hausmann, A., Heitzsch, O., Hommel, M., Kriz, J., Penka, S., Raffin, P., Robin, C., Sperlich, H.P., Ungar, F., and Zitzelsberger, A.E.: 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.Google Scholar
7Tu, K.N., Yeh, C.C., Liu, C.Y., and Chen, C.: Effect of current crowding on vacancy diffusion and void formation in electromigration. Appl. Phys. Lett. 76, 988 (2000).CrossRefGoogle Scholar
8Park, Y.B. and Jeon, I.S.: Effects of mechanical stress at no current stressed area on electromigration reliability of multilevel interconnects. Microelectron. Eng. 71, 76 (2004).Google Scholar
9Jeon, I.S. and Park, Y.B.: Analysis of the reservoir effect on electromigration reliability. Microelectron. Reliab. 44, 917 (2004).Google Scholar
10Vairagar, A.V., Mhaisalkar, S.G., Krishnamoorthy, A., Tu, K.N., Gusak, A.M., Meyer, M.A., and Zschech, E.: In situ observation of electromigration-induced void migration in dual-damascene Cu interconnect structures. Appl. Phys. Lett. 85, 2502 (2004).CrossRefGoogle Scholar
11Gan, C.L., Thompson, C.V., Pey, K.L., Chio, W.K., Tay, H.L., Yu, B., and Radhakrishnan, M.K.: Effect of current direction on the lifetime of different levels of Cu dual-damascene metallization. Appl. Phys. Lett. 79, 4592 (2001).CrossRefGoogle Scholar
12Filippi, R.G., Biery, G.A., and Wachnik, R.A.: The electromigration short-length effect in Ti–AlCu–Ti metallization with tungsten studs. J. Appl. Phys. 78, 3756 (1995).Google Scholar
13Ho, P.S.: Motion of inclusion induced by a direct current and a temperature gradient. J. Appl. Phys. 41, 64 (1970).CrossRefGoogle Scholar
14Zhdanov, V.P.: Elementary Physicochemical Processes on Solid Surfaces, (Plenum Press, New York, 1991), p. 52.CrossRefGoogle Scholar
15Gutzwiller, M.C.: Dislocations and elections in metals, in Atomic and Electronic Structure of Metals, edited by Gilman, J.J. and Tiller, W.A. (ASM, Metals Park, OH, 1966), p. 231.Google Scholar
16Simmons, R.O. and Balluffi, R.W.: Measurement of equilibrium concentrations of vacancies in copper. Phys. Rev. 129, 1533 (1963).CrossRefGoogle Scholar
17Vairagar, A.V., Mhaisalkar, S.G., Krishnamoorthy, A., Meyer, M.A., Zschech, E., Tu, K.N., and Gusak, A.M.: Direct evidence of electromigration failure mechanism in dual-damascene Cu interconnect tree structures. Appl. Phys. Lett. 87, 081909 (2005).Google Scholar