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Relieving the current crowding effect in flip-chip solder joints during current stressing

Published online by Cambridge University Press:  01 January 2006

S.W. Liang ,
T.L. Shao ,
Chih Chen ,
Everett C.C. Yeh  and
K.N. Tu
S.W. Liang
Affiliation:
National Chiao Tung University, Department of Material Science and Engineering, Hsin-chu 30050, Taiwan, Republic of China
T.L. Shao
Affiliation:
National Chiao Tung University, Department of Material Science and Engineering, Hsin-chu 30050, Taiwan, Republic of China
Chih Chen*
Affiliation:
National Chiao Tung University, Department of Material Science and Engineering, Hsin-chu 30050, Taiwan, Republic of China
Everett C.C. Yeh
Affiliation:
FrontAnD Technology, Hsinchu 30050, Taiwan, Republic of China
K.N. Tu
Affiliation:
Department of Materials Science and Engineering, University of California—Los Angeles, Los Angeles, California 90095
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

Three-dimensional simulations for relieving the current crowding effect in solder joints under current stressing were carried out using the finite element method. Three possible approaches were examined in this study, including varying the size of the passivation opening, increasing the thickness of Cu underbump metallization (UBM), and adopting or inserting a thin highly resistive UBM layer. It was found that the current crowding effect in the solder bump could be successfully relieved with the thick Cu UBM or with the highly resistive UBM. Compared to the solder joint with Al/Ni(V)/Cu UBM, for instance, the maximum current density in a solder bump decreased dramatically by a factor of fifteen, say from 1.11 × 105 A/cm2 to 7.54 × 103 A/cm2 when a 20-μm-thick Cu UBM was used. It could be lowered by a factor of seven, say to 1.55 × 104 A/cm2, when a 0.7-μm UBM of 14770 μΩ cm was adopted. It is worth noting that although a resistive UBM layer was used, the penalty on overall resistance increase was negligible because the total resistance was dominated by the Al trace instead of the solder bump. Thermal simulation showed that the average temperature increase due to Joule heating effect was only 2.8 °C when the solder joints with UBM of 14770 μΩ cm were applied by 0.2 A.

Keywords

ElectromigrationPackaging
Type
Articles
Information
Journal of Materials Research , Volume 21 , Issue 1 , January 2006 , pp. 137 - 146
Copyright
Copyright © Materials Research Society 2006

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References

REFERENCES

1.Glenn, R.: Blackwell, The Electronic Packaging Handbook, CRC Press in cooperation with IEEE Press, Boca Raton, FL (2000).Google Scholar
2.The International Technology Roadmap for Semiconductor (Semiconductor Industry Association, San Jose, CA, 2003).Google Scholar
3.Tu, K.N.: Recent advances on electromigration in very-large-scale-integration of interconnects. J. Appl. Phys. 94, 5451 (2003).CrossRefGoogle Scholar
4.Brandenburg, S. and Yeh, S.: Electromigration studies of flip chip bump solder joints, in Proceedings of Surface Mount International Conference and Exhibition, San Jose, CA (SMTA, Edina MN 1998), p. 337.Google Scholar
5.Liu, C.Y., Chen, C., Liao, C.N. and Tu, K.N.: Microstructure-electromigration correlation in a thin strips of eutectic SnPb solder stressed between Cu electrodes. Appl. Phys. Lett. 75, 58 (1999).CrossRefGoogle Scholar
6.Ho, P.S. and Kwok, T.: Electromigration in metals Rep. Prog. Phys. 52, 301 (1989).CrossRefGoogle Scholar
7.Hu, C.K. and Harper, J.M.E.: Copper interconnections and reliability. Mater. Chem. Phys. 52, 5 (1998).CrossRefGoogle Scholar
8.Yeh, E.C.C., Choi, W.J. and Tu, K.N.: Current-crowding-induced electromigration failure in flip chip solder joints. Appl. Phys. Lett. 80(4), 580 (2002).CrossRefGoogle Scholar
9.Choi, W.J., Yeh, ECC. and Tu, K.N.: Mean-time-to-failure study of flip chip solder joints on Cu/Ni(V)/Al thin-film under-bump-metallization. J. Appl. Phys. 94, 5665 (2003).CrossRefGoogle Scholar
10.Nah, J.W., Paik, K.W. and Suh, J.O.: Mechanism of electromigration-induced failure in the 97Pb–3Sn and 37Pb–63Sn composite solder joints. J. Appl. Phys. 94, 7560 (2003).CrossRefGoogle Scholar
11.Wu, J.D., Lee, C.W., Zheng, P.J., Lee, J.C.B., and Li, S.: Electromigration reliability of SnAgxCuy flip chip interconnects, in 2004 Electronic Components and Technology Conference (IEEE, New York) p. 961.Google Scholar
12.Shao, T.L., Chiu, S.H., Chen, C., Yao, D.J. and Hsu, C.Y.: J. Electron. Mater. 33, 1350 (2004).CrossRefGoogle Scholar
13.Tom, T.Y. Lee, Lee, T.Y., and Tu, K.N.: A study of electromigration in 3D flip chip solder joint using numerical simulation of heat flux and current density, in Proceedings of the 51th Electronic Components and Technology Conference, Packaging, and Manufacturing Technology Society, (2001), p. 558.Google Scholar
14.Jang, J.W., Ramanathan, L.N., Lin, J.K. and Frear, D.R.: Spalling of Cu3Sn intermetallics in high-lead 95Pb5Sn solder bumps on Cu under bump metallization during solid-state annealing. J. Appl. Phys. 95, 8286 (2004).CrossRefGoogle Scholar