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Understanding stress gradients in microelectronic metallization

Published online by Cambridge University Press:  15 June 2012

Conal E. Murray ,
E. Todd Ryan ,
Paul R. Besser ,
Christian Witt ,
Jean L. Jordan-Sweet  and
Michael F. Toney
Conal E. Murray*
Affiliation:
IBM T.J. Watson Research Center, Yorktown Heights, New York
E. Todd Ryan
Affiliation:
GLOBALFOUNDRIES, Albany Nanotech Center, Albany, New York
Paul R. Besser
Affiliation:
GLOBALFOUNDRIES, Sunnyvale, California
Christian Witt
Affiliation:
GLOBALFOUNDRIES, T.J. Watson Research Center, Yorktown Heights, New York
Jean L. Jordan-Sweet
Affiliation:
IBM T.J. Watson Research Center, Yorktown Heights, New York
Michael F. Toney
Affiliation:
Stanford Synchrotron Radiation Lightsource, Menlo Park, California
*
a)Author to whom correspondence should be addressed. Electronic mail: conal@us.ibm.com
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Abstract

The manufacture of ultra-large scale integration technology can impose significant strain within the constituent metallization because of the mismatch in coefficients of thermal expansion between metallization and its surrounding environment. The resulting stress distributions can be large enough to induce voiding within Cu-based metallization, a key reliability issue that must be addressed. The interface between the Cu and overlying capping layers is a critical location associated with void formation. By combining conventional and glancing-incidence X-ray diffraction, depth-dependent stress distributions that develop in Cu films and patterned features are investigated. In situ annealing and as-deposited measurements reveal that strain gradients are created in capped Cu structures, where an increased in-plane tensile stress is generated near the Cu/cap interface. The interplay between plasticity in Cu and the constraint imposed by capping layers dictates the extent of the observed gradients. Cu films possessing caps deposited at temperatures where Cu experienced only elastic deformation did not exhibit depth-dependent stress distributions. However, all capped Cu samples exposed to temperatures that induce plastic behavior developed greater tensile stress at the Cu/cap interface than in the bulk Cu film after cooling, representing a clear concern for the mitigation of metallization voiding.

Keywords

X-ray diffractionmicroelectronicscopperstress
Type
Technical Articles
Information
Powder Diffraction , Volume 27 , Issue 2 , June 2012 , pp. 92 - 98
Copyright
Copyright © International Centre for Diffraction Data 2012

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References

Dölle, H. and Hauk, V. (1976). “Röntgenographische Spannungsermittlung der Eigenspannungssysteme allgemeiner Orientierun,” Harterei-Tech. Mitt. 31, 165–168.Google Scholar
Flinn, P. A. (1991). “Measurement and interpretation of stress in copper films as a function of thermal history,” J. Mater. Res. 6, 1498–1501.CrossRefGoogle Scholar
Gambino, J. P., Lee, T. C., Chen, F., and Sullivan, T. D. (2009). “Reliability of copper interconnects: stress-induced voids,” ECS Trans. 18, 205–211.CrossRefGoogle Scholar
Gan, D., Ho, P. S., Pang, Y., Huang, R., Leu, J., Maiz, J., and Scherban, T. (2006). “Effect of passivation on stress relaxation in electroplated copper films,” J. Mater. Res. 21, 1512–1518.Google Scholar
Himuro, T. and Takayama, S. (2005). “Temperature dependence of stress distribution in depth for Cu thin films,” Mat. Res. Soc. Symp. Proc. 854E, U11.11.Google Scholar
Hu, C-K., Canaperi, D., Chen, S. T., Gignac, L. M., Herbst, B., and Kaldor, S. (2004). “Effects of overlayers on electromigration reliability improvement for Cu/low k interconnects”, IEEE 42nd International Reliability Physics Symposium, 222–228.Google Scholar
Keller, R-M., Baker, S. P., and Arzt, E. (1998). “Quantitative analysis of strengthening mechanisms in thin Cu films: effects of film thickness, grain size and passivation,” J. Mater. Res. 13, 1307–1317.Google Scholar
Murray, C. E., Besser, P. R., Witt, C., and Jordan-Sweet, J. L. (2008). “Stress gradients induced in Cu films by capping layers,” Appl. Phys. Lett. 93, 221901.Google Scholar
Murray, C. E., Besser, P. R., Witt, C., and Toney, M. F. (2010a). “In situ evolution of stress gradients in Cu films induced by capping layers,” Appl. Phys. Lett. 96, 261903.Google Scholar
Murray, C. E., Besser, P. R., Witt, C., and Jordan-Sweet, J. L. (2010b). “Stress gradients observed in Cu thin films induced by capping layers,” J. Mater. Res. 25, 622–628.CrossRefGoogle Scholar
Murray, C. E., Besser, P. R., Ryan, E. T., and Jordan-Sweet, J. L. (2011a). “Triaxial stress distributions in Cu/low-k dielectric interconnect features,” Appl. Phys. Lett. 98, 061908.CrossRefGoogle Scholar
Murray, C. E., Besser, P. R., Ryan, E. T., and Jordan-Sweet, J. L. (2011b). “Evolution of stress gradients in Cu films and features induced by capping layers,” Microelectronic Eng. (In press).Google Scholar
Noyan, I. C. and Cohen, J. B. (1987). Residual Stress (Springer-Verlag, New York), 122.Google Scholar
Parratt, L. G. (1954). “Surface studies of solids by total reflection of X-rays,” Phys. Rev. 95, 359–369.CrossRefGoogle Scholar
Schute, C. J. and Cohen, J. B. (1991). “Strain gradients in Al-2% Cu thin films,” J. Appl. Phys. 70, 2104–2110.Google Scholar
Shen, Y-L. and Ramamurty, U. (2003). “Temperature-dependent inelastic response of passivated copper films: experiments, analyses and implications,” J. Vac. Sci. Tech. B. 21, 1258–1264.CrossRefGoogle Scholar
Takayama, S., Oikawa, M., and Himuro, T. (2004). “Thermal stability and internal stress for strongly (111) oriented Cu films,” Mat. Res. Soc. Symp. Proc. 795, U5.11.Google Scholar
Thouless, M. D., Gupta, J., and Harper, J. M. E. (1993). “Stress development and relaxation in copper films during thermal cycling,” J. Mater. Res. 8, 1845–1852.CrossRefGoogle Scholar
Toney, M. F. and Brennan, S. (1989). “Observation of the effect of refraction on x rays diffracted in a grazing-incidence asymmetric Bragg geometry,” Phys. Rev. B, 39, 7963–7966.CrossRefGoogle Scholar
Vinci, R. P., Zielinski, E. M., and Bravman, J. C. (1995). “Thermal strain and stress in copper thin films,” Thin Solid Films, 262, 142–153.CrossRefGoogle Scholar
Wilson, C. J., Croes, K., Zhao, C., Metzger, T. H., Zhao, L., Beyer, G. P., Horsfall, A. B., O'Neill, A. G., and Tokei, Z. (2009). “Synchrotron measurement of the effect of linewidth scaling on stress in advanced Cu/low k interconnects,” J. Appl. Phys. 106, 053524.CrossRefGoogle Scholar
Winholz, R. A. and Cohen, J. B. (1988). “Generalised least-squares determination of triaxial stress states by X-ray diffraction and the associated errors,” Aust. J. Phys. 41, 189–199.CrossRefGoogle Scholar