Reduction of Leakage Current Along Polyimide Layers in Wafer Level Packaging

  • Tae Kyu Kang
  • Hyung Gyoo LeeEmail author
Regular Paper


Wafer level packaging (WLP) has become the backbone technology for chip-scale packaging and 3D integration used in compact, light-weight, and multifunctional electronic systems. Metal redistribution lines (RDL) and insulating polymer layers are the core constituents of WLP and the lateral leakage current between close-spaced RDLs have been a major concern for the electrical reliability in a dense package. In this article, it is demonstrated that Ar plasma related polyimide (PI) damage is the main cause of leakage current rather than metal residue from the RDL wet etch on the polymer surface. Through the optimization of the etch conditions after the PI descumming process by lowering RF power and raising ICP power for plasma, the leakage current of 1.6 μA is reduced to less than 5 nA. Furthermore, a model is proposed to explain the current conduction along the damaged PI layers. The results will be applicable to the fabrication of electronic devices and circuits on plastic substrate utilizing plasma-assisted processes.


Wafer level packaging (WLP) Polyimide Leakage current Frenkel–Poole conduction Plasma damage 



The work of Hyung Gyoo Lee was financially supported by the Research Year of Chungbuk National University in 2016.


  1. 1.
    P. Garrou, C. Bower, P. Ramm, Handbook of 3D Integration (Wiley, Hoboken, 2007), pp. 1–11Google Scholar
  2. 2.
    M. Topper, T. Fischer, T. Baumgartner, H. Reichl.
  3. 3.
  4. 4.
    H.-P. Pu, H.J. Kuo, C.S. Liu, D.C.H. Yu.
  5. 5.
  6. 6.
    D. Chen, C.M. Lai, K.H. Tan, L. Zhang, X. Long.
  7. 7.
  8. 8.
  9. 9.
    S.-J. Cho, J.-W. Choi, I.-S. Bae, T. Nguyen, J.-H. Boo, Jpn. J. Appl. Phys. 50, 01AK02 (2011)CrossRefGoogle Scholar
  10. 10.
    C. Kim, D. Jeong, J. Hwang, H. Chae, C.-K. Kim, J. Korean Phys. Soc. 54(2), 621 (2009)CrossRefGoogle Scholar
  11. 11.
    A.B. Meddeb, Z. Ounaies, M. Lanagan, Chem. Phys. Lett. 649, 111 (2016)CrossRefGoogle Scholar
  12. 12.
    N. Inagaki, S. Tasaka, S. Shimada, N. Inagakil, J. Appl. Polym. Sci. 79, 808 (2001)CrossRefGoogle Scholar
  13. 13.
    G.G. Raju, R. Shaikh, S.U. Haq, IEEE Trans. Electr. Insulation 15(3), 663 (2008)CrossRefGoogle Scholar
  14. 14.
    G.M. Sessler, B. Hahn, D.Y. Yoon, J. Appl. Phys. 60(1), 318 (1986)CrossRefGoogle Scholar
  15. 15.
    J.-H. Park, J.-H. Lee, A. Soon, Phys. Chem. Chem. Phys. 18, 21893 (2016)CrossRefGoogle Scholar

Copyright information

© The Korean Institute of Electrical and Electronic Material Engineers 2019

Authors and Affiliations

  1. 1.Department of Electronics and Information EngineeringChungbuk National UniversityCheongjuKorea

Personalised recommendations