Abstract
The interfacial reactions in Cu/Sn–52In/Cu interconnects during solid–solid (S–S) and liquid–solid (L–S) electromigration (EM) under a current density of 2.0 × 104 A/cm2 at 90 and 150 °C have been in situ studied using synchrotron radiation real-time imaging technology. The In atoms directionally migrate toward the cathode due to the back-stress induced by the preferential migration of the Sn atoms over the In atoms toward the anode during the S–S EM, resulting in the segregation of the Sn and In atoms at the anode and cathode, respectively. During the L–S EM, however, the In atoms directionally migrate toward the anode due to the negative effective charge number (Z*) of In rather than the back-stress. The polarity effect, i.e., the intermetallic compounds growing continuously at the anode while becoming thinner at the cathode, is more significant during the L–S EM than the S–S EM. Furthermore, the consumption rate of the cathode Cu during the L–S EM is three orders of magnitude higher than that in the case of the S–S EM because of the significantly higher EM-induced atomic flux in the liquid solder. The migrations of the Sn, In, and Cu atoms are discussed in terms of diffusion flux.
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References
Y. Jung and J. Yu: Electromigration induced Kirkendall void growth in Sn-3.5Ag/Cu solder joints. J. Appl. Phys. 115, 083708 (2014).
C. Chen, H.M. Tong, and K.N. Tu: Electromigration and thermomigration in Pb-free flip-chip solder joints. Annu. Rev. Mater. Sci. 40, 531 (2010).
Y.H. Lin, Y.C. Hu, C.M. Tsai, C.R. Kao, and K.N. Tu: In situ observation of the void formation-and-propagation mechanism in solder joints under current-stressing. Acta Mater. 53, 2029 (2005).
J.R. Cahoon: A modified “hole” theory for solute impurity diffusion in liquid metals. Metall. Mater. Trans. A 28, 583 (1997).
M.L. Huang, Z.J. Zhang, N. Zhao, and Q. Zhou: A synchrotron radiation real-time in situ imaging study on the reverse polarity effect in Cu/Sn–9Zn/Cu interconnect during liquid–solid electromigration. Scr. Mater. 68, 853 (2013).
M.L. Huang, Q. Zhou, N. Zhao, and Z.J. Zhang: Abnormal diffusion behavior of Zn in Cu/Sn–9wt.% Zn/Cu interconnects during liquid–solid electromigration. J. Electron. Mater. 42, 2975 (2013).
M.L. Huang, Q. Zhou, N. Zhao, X.Y. Liu, and Z.J. Zhang: Reverse polarity effect and cross-solder interaction in Cu/Sn–9Zn/Ni interconnect during liquid-solid electromigration. J. Mater. Sci. 49, 1755 (2014).
M.L. Huang, Z.J. Zhang, N. Zhao, and F. Yang: In situ study on reverse polarity effect in Cu/Sn–9Zn/Ni interconnect undergoing liquid–solid electromigration. J. Alloys Compd. 619, 667 (2015).
X. Gu and Y.C. Chan: Electromigration in line-type Cu/Sn–Bi/Cu solder joints. J. Electron. Mater. 37, 1721 (2008).
C.N. Liao, C.P. Chung, and W.T. Chen: Electromigration-induced Pb segregation in eutectic Sn–Pb molten solder. J. Mater. Res. 20, 3425 (2005).
J.R. Huang, C.M. Tsai, Y.W. Lin, and C.R. Kao: Pronounced electromigration of Cu in molten Sn-based solders. J. Mater. Res. 23, 250 (2008).
T.H. Chuang, C.L. Yu, S.Y. Chang, and S.S. Wang: Phase identification and growth kinetics of the intermetallic compounds formed during In–49Sn/Cu soldering reactions. J. Electron. Mater. 31, 640 (2002).
J.P. Daghfal and J.K. Shang: Current-induced phase partitioning in eutectic indium-tin Pb-free solder interconnect. J. Electron. Mater. 36, 1372 (2007).
L.D. Chen, M.L. Huang, and S.M. Zhou: Effect of electromigration on intermetallic compound formation in line-type Cu/Sn/Cu interconnect. J. Alloys Compd. 504, 535 (2010).
H. Gan and K.N. Tu: Polarity effect of electromigration on kinetics of intermetallic compound formation in Pb-free solder V-groove samples. J. Appl. Phys. 97, 063514 (2005).
H. Conrad: Effect of electric current on solid-state phase transformations in metals. Mater. Sci. Eng., A 287, 227 (2000).
P.S. Ho and T. Kwok: Electromigration in metals. Rep. Prog. Phys. 52, 301 (1989).
H.B. Huntington and A.R. Gron: Current-induced marker motion in gold wires. J. Phys. Chem. Solids 20, 76 (1961).
P. Kumar, J. Howarth, and I. Dutta: Electric current induced flow of liquid metals: Mechanism and substrate-surface effects. J. Appl. Phys. 115, 044915 (2014).
M.D. Smolin and I.N. Frantsevich: Application of the method of electric transport to the study of metals and alloys. Sov. Phys-Sol 3, 1536 (1961).
ACKNOWLEDGMENTS
This work is supported by the National Natural Science Foundation of China under Grant Nos. 51475072 and 51171036, and the BL13W1 beam line of Shanghai Synchrotron Radiation Facility (SSRF).
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Huang, M., Zhang, Z., Zhao, N. et al. Migration behavior of indium atoms in Cu/Sn–52In/Cu interconnects during electromigration. Journal of Materials Research 30, 3316–3323 (2015). https://doi.org/10.1557/jmr.2015.281
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DOI: https://doi.org/10.1557/jmr.2015.281