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Grain Boundary Chemistry in Al-Cu Metallizations as Determined by Analytical Electron Microscopy

Published online by Cambridge University Press:  15 February 2011

J. R. Michael ,
A. D. Romig Jr.  and
D. R. Frear
J. R. Michael
Affiliation:
Materials and Process Sciences Directorate, Sandia National Laboratories Albuquerque, NM 87185
A. D. Romig Jr.
Affiliation:
Materials and Process Sciences Directorate, Sandia National Laboratories Albuquerque, NM 87185
D. R. Frear
Affiliation:
Materials and Process Sciences Directorate, Sandia National Laboratories Albuquerque, NM 87185
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Abstract

Al with additions of Cu is commonly used as the conductor metallizations for integrated circuits (ICs). As the packing density of ICs increases, interconnect lines are required to carry ever higher current densities. Consequently, reliability due to electromigration failure becomes an increasing concern. Cu has been found to increase the lifetimes of these conductors, but the mechanism by which electromigration is improved is not yet fully understood. In order to evaluate certain theories of electromigration it is necessary to have a detailed description of the Cu distribution in the Al microstructure, with emphasis on the distribution of Cu at the grain boundaries. In this study analytical electron microscopy (AEM) has been used to characterize grain boundary regions in an Al-2 wt.% Cu thin film metallization on Si after a variety of thermal treatments. The results of this study indicate that the Cu distribution is dependent on the thermal annealing conditions. At temperatures near the θ phase (CuAl2) solvus, the Cu distribution may be modelled by the collector plate mechanism, in which the grain boundary is depleted in Cu relative to the matrix. At lower temperatures, Cu enrichment of the boundaries occurs, perhaps as a precursor to second phase formation. Natural cooling from the single phase field produces only grain boundary depletion of Cu consistent with the collector-plate mechanism. The kinetic details of the elemental segregation behavior derived from this study can be used to describe microstructural evolution in actual interconnect alloys.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 229: Symposium Q – Structure/Property Relationships for Metal/Metal Interfaces , 1991 , 303
Copyright
Copyright © Materials Research Society 1991

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References

1. d'Huerle, F., Proc, IEEE, 59 1409 (1971).CrossRefGoogle Scholar
2. Ames, I., d'Heuerle, F. M. and Horstmann, R. E., IBM J. Res. and Dev., 14, 461 (1970).Google Scholar
3. d'Huerle, F. M., Met.Trans, 2, 683 (1971).Google Scholar
4. Artz, E. and Nix, W. D., J. Mater. Res., 6, 731 (1991).Google Scholar
5. Learn, A. J., J. Elec. Mat., 3, 531 (1974).Google Scholar
6. Ho, P.S.,. Phys. Rev. B., 8, 4534 (1973).CrossRefGoogle Scholar
7. Reddy, K. V., Beniere, F. and Kostpoulus, D., J. Appl, phys., 50, 2782 (1979).CrossRefGoogle Scholar
8. Frear, D. R., Sanchez, J. E., Romig, A. D. Jr.and Morris, J. W. Jr., Met. Trans A., 21A. 2449 (1990).Google Scholar
9. Michael, J. R. and Williams, D. B., J. Microsc., 14, 289 (1987).Google Scholar
10. Michael, J. R., Williams, D. B., Klein, C. F. and Ayer, R., J. Microsc., 160, 41 (1990).Google Scholar
11. Goldstein, J. I., Costley, J. L., Lorimer, G. W. and Reed, S. J. B., in Scanning Electron Microscopy, edited by Johari, O. (IITRI, Chicago, 1977) p. 315–324.Google Scholar
12. Aaron, H. B. and Aaronson, H. I., Acta Met., 16, 789 (1968).CrossRefGoogle Scholar