Abstract
The thermal stability of flip-chip solder joints made with trilayer Al/Ni(V)/Cu underbump metalization (UBM) and eutectic Pb-Sn solder connected to substrates with either electroless Ni(P)-immersion gold (ENIG) or Pb-Sn solder on Cu pad (Cu-SOP) surface finish was determined. The ENIG devices degraded more than 50 times faster than the Cu-SOP devices. Microstructural characterization of these joints using scanning and transmission electron microscopy and ion beam microscopy showed that electrical degradation of the ENIG devices was a direct result of the conversion of the as-deposited Ni(V) barrier UBM layer into a porous fine-grained V3Sn-intermetallic compound (IMC). This conversion was driven by the Au layer in the ENIG surface finish. No such conversion was observed for the devices assembled on Cu-SOP surface finish substrates. A resistance degradation model is proposed. The model captures changes from a combination of phenomena including increased (1) intrinsic resistivity, (2) porosity, and (3) electron scattering at grain boundaries and surfaces. Finally, the results from this study were compared with results found in a number of published electromigration studies. This comparison indicates that degradation during current stressing in the Pb-Sn bump/ENIG system is in part due to current-crowding-induced Joule heating and the thermal gradients that result from localized Joule heating.
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References
L.F. Miller, IBM J. Res. Dev., 250 (1969).
see for example, J.H. Lau, Low Cost Flip Chip Technologies (New York: McGraw-Hill, 2000), chapter 2.
B. Ebersberger, R. Bauer, and L. Alexa, Proc. 54th Electron. Comp. and Tech. Conf. (2004), p. 683.
J.H. Lee, J.H Park, D.H. Shin, Y.H. Lee, and Y.S. Kim, J. Electron. Mater., 30, 1138 (2001).
C.E. Ho, L.C. Shiau, and C.R. Kao, J. Electron. Mater., 31, 1264 (2002).
K. Zeng, V. Vuorinen, Y.L. Lin, and C.R. Kao, J. Electron. Mater., 31, 584 (2002).
K·S. Kim, S·H. Huh, and Suganama, J. Alloys and Compounds, 352, 226 (2003).
A. Zribi, R. Kinyanjui, P. Borgesen, L. Zavalij, and E.J. Cotts, J. Electron. Mater., 54, 38 (2002).
S·K. Kang, D.Y. Shih, K. Fogel, P. Lauro, M.J. Yim, G.G. Advocate jr., M. Giffin, C. Goldsmith, D.W. Henderson, T.A. Gosselin, D.E. King, J.J. Konrad, A. Sarkhel, and K.J. Puttlitz, IEEE Trans. On Electron. Pkg. Manuf., 25, 155 (2002).
M.O. Alam, Y.C. Chan, and K·N. Tu, Chemistry of Mater., 15, 4340 (2003).
Y.D. Jeon, K·W. Paik, A. Ostmann, and H. Reichl, J. Electron. Mater., 34, 80 (2005).
W.T. Chen, C.E. Ho, and C.R. Kao, J. Mater. Res., 17, 2109 (2003).
K. Zeng and K·N Tu, Mater. Science and Eng., R.38, 55 (2002).
C.E. Ho, Y.W. Lin, S.C. Yang, and C.R. Kao, Proc. 55th Electron. Comp. and Tech. Conf. (2005), p. 1134.
K. O’Donnell, Lead Free Electron., 1 (2004).
A.M. Minor and J.W. Morris jr., Metall. Mater. Trans. A, 31A, 798 (2000).
F. Zhang, C.C. Chum, and M. Li, Proc. 52th Electron. Comp. and Tech. Conf. (2002), p. 726.
L.C. Shiau, C.E. Ho, and C. R.Kao, Solder and Surface Mount Tech., 14/3, 25 (2002).
T. Laurila, V. Vuorinen, T. Mattila, and J.K. Kivilahti, J. Electron. Mater., 34, 103 (2005).
F. Stepniak, Proc. IMAPS (1999), p. 427.
F. Stepniak, Microelectron. Rel., 41, 735 (2001).
IPC-7095 (August 2000).
R.J. Fields and S.R Low, Materials Performance Group Research Publication, http://www.metallurgy.nist.gov/mechanical_properties/solder_paper.html (2005).
W. Riedel, Electroless Nickel Plating (Metal Park, Ohio: ASM International, 1991), p. 103.
N. Morton, B·W. James, G.H. Wostenholm, and N.A. Howard, J. Less-Common Metals, 64, 69 (1979).
C. Case, ITRS Report Party 3: Interconnect, Solid State Technol. (March 2005).
J.R. Black, IEEE Trans. Electron Devices ED-16, 338 (1969).
S. Brandenburg and S. Yeh, Proc. SMI 98 (1998), p. 337.
W.J. Choi, E.C·C. Yeh, and K·N. Tu, J. Appl. Phys., l94, 5665 (2003).
Y.L. Lin, Y.S. Lai, C.M. Tsai, and C.R. Kao, J. Electron. Mater., 35, 2147 (2006).
Acknowledgement
The authors would like to thank Dr. S. Mohoney for supplying Ref. 25.
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Osenbach, J., Amin, A., Bachman, M. et al. Stability of Flip-Chip Interconnects Assembled with Al/Ni(V)/Cu-UBM and Eutectic Pb-Sn Solder During Exposure to High-Temperature Storage. J. Electron. Mater. 38, 303–324 (2009). https://doi.org/10.1007/s11664-008-0599-9
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DOI: https://doi.org/10.1007/s11664-008-0599-9