Mechanical Characterization of Multilayer Thin Film Stacks Containing Porous Silica Using Nanoindentation and the Finite Element Method


Novel metal/dielectric material combinations are becoming increasingly important for reducing the resistance-capacitance (RC) interconnection delay within integrated circuits (ICs) as the device dimensions shrink to the sub-micron scale. Copper (Cu) is the material of choice for metal interconnects and SiO2 (with a dielectric constant k = ∼ 3.9) has been used as an interlevel dielectric material in the industry. To meet the demands of the international road map for semiconductors, materials with a significantly lower dielectric constant are needed. In this study, the effects of porosity and layer thicknesses on the mechanical properties of a multilayer thin film (Cu, Ta and SiO2)-substrate (Si) system are examined using nanoindentation and finite element (FE) simulations. A micromechanics model is first developed to predict the stress-strain relation of the porous silica based on the homogenization method for composite materials. An FE model is then generated and validated to perform a parametric study on nanoindentation of the Cu/Ta/SiO2/Si system aiming to predict the mechanical properties of the multilayer film stack.

This is a preview of subscription content, access via your institution.


  1. 1.

    K. Maex, M. R. Baklanov, D. Shamiryan, F. Iacopi, S. H. Brongersma, Z. S. Yanovitskaya, J. Appl. Phys. 93, 8793 (2003).

    CAS  Article  Google Scholar 

  2. 2.

    W. C. Oliver, G. M. Pharr, MRS Bull. 17, 28–33 (1992).

    Google Scholar 

  3. 3.

    F. Iskandar, M. Abdullah, H. Yoden, K. Okuyama, J. Appl. Phys. 93, 9237 (2003).

    CAS  Article  Google Scholar 

  4. 4.

    J. A. Knapp, D. M. Follstaedt, S. M. Myers, J. C. Barbour, T. A. Friedmann, J. Appl. Phys. 85, 1460 (1999).

    CAS  Article  Google Scholar 

  5. 5.

    F. Iacopi, S. H. Brongersma, B. Vandevelde, M. O’Toole, D. Degryse, Y. Travaly, K. Maex, Microelectron. Eng. 75, 54 (2004).

    CAS  Article  Google Scholar 

  6. 6.

    K. Li, X.-L. Gao, G. Subhash, Int. J. Solids Struct. 42, 1777 (2005).

    Article  Google Scholar 

  7. 7.

    P. Vena, D. Gastaldi, Compos.: Part B 36, 115 (2005).

    Article  Google Scholar 

  8. 8.

    H. Pelletier, J. Krier, A. Cornet, P. Mille, Thin Solid Films 379, 147 (2000).

    CAS  Article  Google Scholar 

  9. 9.

    National Materials Advisory Board, Coatings for high-temperature structural materials: trends and opportunities (The National Academy of Sciences, 1996), p. 18.

  10. 10.

    H. E. Boyer, Atlas of Stress-Strain Curves (ASM, Metals Park, OH, 1987).

    Google Scholar 

  11. 11.

    A. K. Bhattacharya, W. D. Nix, Int. J. Solids Struct. 24, 1287 (1988).

    Article  Google Scholar 

  12. 12.

    A. A. Volinsky, W. W. Gerberich, Microelectron. Eng. 69, 519 (2003).

    CAS  Article  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Ke Li.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Li, K., Mudhivarthi, S., Saigal, S. et al. Mechanical Characterization of Multilayer Thin Film Stacks Containing Porous Silica Using Nanoindentation and the Finite Element Method. MRS Online Proceedings Library 875, 23 (2005).

Download citation