Electronic Materials Letters

, Volume 15, Issue 2, pp 149–158 | Cite as

Ni Barrier Symmetry Effect on Electromigration Failure Mechanism of Cu/Sn–Ag Microbump

  • Gyu-Tae Park
  • Byeong-Rok Lee
  • Kirak Son
  • Young-Bae ParkEmail author
Original Article - Electronics, Magnetics and Photonics


Ni barrier symmetry effect on the electromigration (EM) failure mechanism of Cu/Sn–Ag microbump were systematically investigated by studying the intermetallic compound (IMC) growth characteristics at 150 °C with a current density of 1.5 × 105 A/cm2. In the symmetric Ni barrier structure, Cu diffusion to Sn–Ag solder was restricted by the Ni barrier at both interfaces and the Ni3Sn4 phase formed by the inter-diffusion between Ni and Sn atoms just after bonding, which was gradually transformed to (Ni,Cu)3Sn4 phase and later to (Cu,Ni)6Sn5 during current stressing with relatively slow resistance increase with time. By the way, in the asymmetric structure, extensive Cu6Sn5 phase grew by the inter-diffusion between Cu and Sn atoms due to there is no Ni barrier at the upper interface, which was rapidly transformed into only Cu6Sn5 and Cu3Sn IMCs during electron downward flow, with relatively fast resistance increase with time. Therefore, the symmetric Ni barrier structure is very effective in restricting extensive IMC reactions during EM of Cu-solder microbump structure.

Graphical Abstract


Microbump Symmetry Ni barrier Electromigration Intermetallic compound 



This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2016R1D1A3B03933937), and also by MOTIE (Ministry of Trade, Industry and Energy (10067804) and KSRC(Korea Semiconductor Research Consortium) support program for the development of the future semiconductor device. The authors would like to thank Dr. M.S. Suh and N.S. Kim from SK Hynix Semiconductor Inc. for valuable discussions and test sample preparations.


  1. 1.
    You, H.Y., Hwang, Y.H., Pyun, J.W., Ryu, Y.G., Kim, H.S.: Chip package interaction in micro bump and TSV structure. In: Proceedings of the 2012 IEEE 62nd Electronic Components and Technology Conference, p. 315. San Diego, CA (2012)Google Scholar
  2. 2.
    Kim, J.H., Yoo, W.S., Han, S.M.: Non-destructive micro-Raman analysis of Si near Cu through silicon via. Electron. Mater. Lett. 13, 120 (2017)CrossRefGoogle Scholar
  3. 3.
    Sharma, A., Jung, D.H., Roh, M.H., Jung, J.P.: Fabrication and shear strength analysis of Sn–3.5Ag/Cu-filled TSV for 3D microelectronic packaging. Electron. Mater. Lett. 12, 856 (2016)CrossRefGoogle Scholar
  4. 4.
    Jin, S.H., Lee, D.R., Lee, W.Y., Lee, S.Y., Lee, M.H.: Seed step-coverage enhancement process for a high-aspect-ratio through-silicon via using a pyrophosphate solution. Met. Mater. Int. 21, 775 (2015)CrossRefGoogle Scholar
  5. 5.
    Hsiao, Y.H., Lin, K.L., Lee, C.W., Shao, Y.H., Lai, Y.S.: Study of electromigration-induced failures on Cu pillar bumps joined to OSP and ENEPIG substrates. J. Electron. Mater. 41, 3368 (2012)CrossRefGoogle Scholar
  6. 6.
    Liu, C.Y., Chen, C., Liao, C.N., Tu, K.N.: Microstructure-electromigration correlation in a thin stripe of eutectic SnPb solder stressed between Cu electrodes. Appl. Phys. Lett. 75, 58 (1999)CrossRefGoogle Scholar
  7. 7.
    Liu, C.Y., Chen, C., Tu, K.N.: Electromigration in Sn–Pb solder strips as a function of alloy composition. J. Appl. Phys. 88, 5703 (2000)CrossRefGoogle Scholar
  8. 8.
    Huynh, Q.T., Liu, C.Y., Chen, C., Tu, K.N.: Electromigration in eutectic SnPb solder lines. J. Appl. Phys. 89, 4332 (2001)CrossRefGoogle Scholar
  9. 9.
    Choi, W.J., Yeh, C.C., 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. 10.
    Tu, K.N., Yeh, C.C., Liu, C.Y., Chen, C.: Effect of current crowding on vacancy diffusion and void formation in electromigration. Appl. Phys. Lett. 76, 988 (2000)CrossRefGoogle Scholar
  11. 11.
    Lai, Y.S., Lee, C.W., Kao, C.L.: Effect of test conditions on electromigration reliability of Sn–Ag–Cu flip-chip solder interconnects. J. Electron. Packag. 129, 56 (2007)CrossRefGoogle Scholar
  12. 12.
    Chang, Y.W., Chen, C., Chang, T.C., Zhan, C.J., Juang, J.Y., Huang, A.T.: Fast phase transformation due to electromigration of 18 μm microbumps in three-dimensional integrated-circuit integration. J. Mater. Lett. 137, 136 (2014)CrossRefGoogle Scholar
  13. 13.
    Heo, M.H., Kang, N., Park, S., Kim, J.K., Hong, W.S.: Kinetics of intermetallic compounds growth induced by electromigration of Sn–0.7Cu solder. Korean J. Met. Mater. 54, 908 (2016)CrossRefGoogle Scholar
  14. 14.
    Xu, D.E., Chow, J., Mayer, M., Jung, J.P., Yoon, J.H.: Sn–Ag–Cu to Cu joint current aging test and evolution of resistance and microstructure. Electron. Mater. Lett. 11, 1078 (2015)CrossRefGoogle Scholar
  15. 15.
    Sharma, A., Xu, D.E., Chow, J., Mayer, M., Sohn, H.R., Jung, J.P.: Electromigration of composite Sn–Ag–Cu solder bumps. Electron. Mater. Lett. 11, 1072 (2015)CrossRefGoogle Scholar
  16. 16.
    Kim, S.H., Lee, B.R., Park, G.T., Kim, J.M., Yoo, S.H., Park, Y.B.: Effects of PCB surface finishes on the mechanical and electrical reliabilities of Sn–0.7Cu Pb-free solder bump. Korean J. Met. Mater. 53, 735 (2015)CrossRefGoogle Scholar
  17. 17.
    Kim, Y., Kwon, J., Yoo, D., Park, S., Lee, D., Lee, D.: Influence of nickel thickness and annealing time on the mechanical properties of intermetallic compounds formed between Cu–Sn solder and substrate. Korean J. Met. Mater. 55, 165 (2017)Google Scholar
  18. 18.
    Alam, M.O., Chan, Y.C.: Solid-state growth kinetics of Ni3Sn4 at the Sn–3.5Ag solder∕Ni interface. J. Appl. Phys. 98, 123527 (2005)CrossRefGoogle Scholar
  19. 19.
    Alam, M.O., Chan, Y.C., Tu, K.N.: Effect of 0.5 wt % Cu addition in Sn–3.5%Ag solder on the dissolution rate of Cu metallization. J. Appl. Phys. 94, 7904 (2003)CrossRefGoogle Scholar
  20. 20.
    Alam, M.O., Chan, Y.C., Tu, K.N.: Elimination of Au-embrittlement in solder joints on Au/Ni metallization. J. Mater. Res. 19, 1303 (2004)CrossRefGoogle Scholar
  21. 21.
    Bader, S., Gust, W., Hieber, H.: Rapid formation of intermetallic compounds interdiffusion in the Cu–Sn and Ni-Sn systems. Acta Metall. Mater. 43, 329 (1995)Google Scholar
  22. 22.
    Kim, P.G., Jang, J.W., Lee, T.Y., Tu, K.N.: Interfacial reaction and wetting behavior in eutectic SnPb solder on Ni/Ti thin films and Ni foils. J. Appl. Phys. 86, 6746 (1999)CrossRefGoogle Scholar
  23. 23.
    Kulojarvi, K., Vuorinen, V., Kivilahti, J.: Effect of dissolution and intermetallic formation on the reliability of FC joints. Microelectron. Int. 15, 20 (1998)CrossRefGoogle Scholar
  24. 24.
    Ghosh, G.: Coarsening kinetics of Ni3Sn4 scallops during interfacial reaction between liquid eutectic solders and Cu/Ni/Pd metallization. J. Appl. Phys. 88, 6887 (2000)CrossRefGoogle Scholar
  25. 25.
    Ghosh, G.: Kinetics of interfacial reaction between eutectic Sn–Pb solder and Cu/Ni/Pd metallizations. J. Electron. Mater. 28, 1238 (1999)CrossRefGoogle Scholar
  26. 26.
    Chae, S.H., Zhang, X., Lu, K.H., Chao, H.L., Ho, P.S., Ding, M., Su, P., Uehling, T., Ramanathan, L.N.: Electromigration statistics and damage evolution for Pb-free solder joints with Cu and Ni UBM in plastic flip-chip packages. J. Mater. Sci. Mater. Electron. 18, 247 (2007)CrossRefGoogle Scholar
  27. 27.
    Liang, S.W., Chang, Y.W., Chen, C.: Relieving hot-spot temperature and current crowding effects during electromigration in solder bumps by using Cu columns. J. Electron. Mater. 36(2), 1348–1354 (2007)CrossRefGoogle Scholar
  28. 28.
    Kuo, K.H., Lee, J., Chien, F.L., Lee, R., Mao, C., Lau, J.: Electromigration performance of Cu pillar bump for flip chip packaging with bump on trace by using thermal compression bonding. In: Proceedings of the 2014 IEEE 64th Electronic Components and Technology Conference, p. 56. Orlando, FL (2014)Google Scholar
  29. 29.
    Yu, J.J., Yang, C.A., Lin, Y.F., Hsueh, C.H., Kao, C.R.: Optimal Ag addition for the elimination of voids in Ni/SnAg/Ni micro joints for 3D IC applications. J. Alloys Compd. 629, 16 (2015)CrossRefGoogle Scholar
  30. 30.
    Liu, Y., Chen, Y.T., Gu, S., Kim, D.W., Tu, K.N.: Fracture reliability concern of (Au, Ni)Sn4 phase in 3D integrated circuit microbumps using Ni/Au surface finishing. Scr. Mater. 119, 9 (2016)CrossRefGoogle Scholar
  31. 31.
    Hsu, H.H., Huang, Y.T., Huang, S.Y., Chang, T.C., Wu, A.T.: Evolution of the intermetallic compounds in Ni/Sn–2.5Ag/Ni microbumps for three-dimensional integrated circuits. J. Electron. Mater. 44, 3888 (2015)CrossRefGoogle Scholar
  32. 32.
    Hsiao, Y.H., Lin, K.L.: The formation and conversion of intermetallic compounds in the Cu pillar Sn–Ag micro-bump with ENEPIG Cu substrate under current stressing. J. Mater. Sci. Mater. Electron. 27, 2201 (2016)CrossRefGoogle Scholar
  33. 33.
    Chen, H.Y., Ku, M.F., Chen, C.: Effect of under-bump-metallization structure on electromigration of Sn–Ag solder joints. Adv. Mater. Res. 1, 83 (2012)CrossRefGoogle Scholar
  34. 34.
    Ceric, H., Pires Singulani, A., Orio, R.L. de Selberherr, S.: Impact of intermetallic compound on solder bump electromigration reliability. In: Proceedings of the 2013 International Conference Simulation of Semiconductor Processes and Devices (SISPAD), p. 73. Glasgow, UK (2013)Google Scholar
  35. 35.
    Chu, M.H., Liang, S.W., Chen, C., Huang, A.T.: Electromigration failure mechanism in Sn–Cu solder alloys with OSP Cu surface finish. J. Electron. Mater. 41, 2502 (2012)CrossRefGoogle Scholar
  36. 36.
    Yoon, J.W., Chun, H.S., Koo, J.M., Lee, H.J., Jung, S.B.: Microstructural evolution of Sn-rich Au–Sn/Ni flip-chip solder joints under high temperature storage testing conditions. Scr. Mater. 56, 661 (2007)CrossRefGoogle Scholar
  37. 37.
    Islam, N., Kim, G., Kim, K.O.: Electromigration for advanced Cu interconnect and the challenges with reduced pitch bumps. In: Proceedings of the 2014 IEEE 64th Electronic Components and Technology Conference, pp. 50–55. Orlando, FL (2014)Google Scholar

Copyright information

© The Korean Institute of Metals and Materials 2018

Authors and Affiliations

  • Gyu-Tae Park
    • 1
  • Byeong-Rok Lee
    • 2
  • Kirak Son
    • 3
  • Young-Bae Park
    • 3
    Email author
  1. 1.Amkor Technology Korea IncGwangjuRepublic of Korea
  2. 2.STATS ChipPAC Korea LtdIncheonRepublic of Korea
  3. 3.School of Materials Science and EngineeringAndong National UniversityAndong-siRepublic of Korea

Personalised recommendations