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A buckling-based metrology for measuring the elastic moduli of polymeric thin films

Nature Materials volume 3, pages 545–550 (2004)Cite this article

Abstract

As technology continues towards smaller, thinner and lighter devices, more stringent demands are placed on thin polymer films as diffusion barriers, dielectric coatings, electronic packaging and so on. Therefore, there is a growing need for testing platforms to rapidly determine the mechanical properties of thin polymer films and coatings. We introduce here an elegant, efficient measurement method that yields the elastic moduli of nanoscale polymer films in a rapid and quantitative manner without the need for expensive equipment or material-specific modelling. The technique exploits a buckling instability that occurs in bilayers consisting of a stiff, thin film coated onto a relatively soft, thick substrate. Using the spacing of these highly periodic wrinkles, we calculate the film's elastic modulus by applying well-established buckling mechanics. We successfully apply this new measurement platform to several systems displaying a wide range of thicknessess (nanometre to micrometre) and moduli (MPa to GPa).

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Figure 1: Experimental protocol and representative images illustrating the buckling instability of a thin polymeric film on a soft silicone sheet.
Figure 2: Modulus measurements of a thickness gradient film of PS.
Figure 3: Modulus versus plasticizer concentration (dioctyl phthalate) for thin PS films.
Figure 4: Modulus versus porosity for a series of nanoporous organosilicate films.

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Acknowledgements

We acknowledge insightful discussions with Rui Huang, Michael J. Fasolka, Jack F. Douglas, Richard A. Register, Edward J. Garboczi and Jan Groenewold. We thank Donald Hunston and Sheng Lin-Gibson for measurement assistance. C.M.S. and C.H. acknowledge the NIST National Research Council Postdoctoral Fellowship Program and funding from the MSEL Director's Reserve Program.

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Author notes

  1. Christopher Harrison

    Present address: Sensor Physics Department, Schlumberger-Doll Research, Ridgefield, Connecticut, 06877, USA

  2. Mark R. VanLandingham

    Present address: Polymers Research Branch, United States Army Research Laboratory, Aberdeen Proving Ground, Maryland, 21005, USA

Authors and Affiliations

  1. Polymers Division, National Institute of Standards and Technology, Gaithersburg, 20899, Maryland, USA

    Christopher M. Stafford, Christopher Harrison, Kathryn L. Beers, Alamgir Karim & Eric J. Amis

  2. Materials and Construction Research Division, National Institute of Standards and Technology, Gaithersburg, 20899, Maryland, USA

    Mark R. VanLandingham

  3. IBM Research Division, Almaden Research Center, San Jose, 95120, California, USA

    Ho-Cheol Kim, Willi Volksen & Robert D. Miller

  4. IBM Research Division, T.J. Watson Research Center, Yorktown Heights, 10598, New York, USA

    Eva E. Simonyi

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  1. Christopher M. Stafford
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Correspondence to Christopher M. Stafford.

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Stafford, C., Harrison, C., Beers, K. et al. A buckling-based metrology for measuring the elastic moduli of polymeric thin films. Nature Mater 3, 545–550 (2004). https://doi.org/10.1038/nmat1175

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