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Testing the viscoelastic properties of SU8 photo resist thin films at different stages of processing by nanoindentation creep and stress relaxation

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Published/Copyright: May 23, 2013
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International Journal of Materials Research
From the journal International Journal of Materials Research Volume 98 Issue 5

Abstract

The viscoelastic properties of SU8-25 photo resist coatings have been investigated by means of nanoindentation creep and stress relaxation tests. Different stages of processing of SU8 have been tested: (a) Spin coating and pre-bake only, (b) exposure to ultraviolet light for different durations, (c) different cross-linking times of the resist and finally (d) the completely processed sample (post-bake, develop and hard-bake). At each stage creep and stress relaxation tests have been performed with loads of 2 mN or indentation depth of 500 nm covering creep/relaxation times from 0.1 s to 1000 s. From the raw data the following viscoelastic functions have been computed: the creep compliance J(t) and relaxation modulus G(t), the relaxation and retardation time spectra H() and L(), and the dynamic viscosity (t). It has been found that different pre-bake times influence the viscosity of the film. The cross-linking of the SU8 starts immediately after exposure even without applying a post-bake. A strong increase in viscosity can be observed within the first 4 h after exposure due to the progress of cross-linking at room temperature. After the finish of cross-linking the dynamic viscosity has increased by 50 times. Observation of impression recovery after unloading over 3 days indicated up to 75 % immediate and retarded elastic recovery for the fully processed film, while the simply pre-baked sample only exhibied 25 % recovery and 75 % irreversible viscous flow.

Keywords: SU8; Nanoindentation; Creep; Relaxation; Viscoelastic properties
* Correspondence address, Dr. Kirsten Ingolf Schiffmann, Fraunhofer Institut für Schicht- und Oberflächentechnik, Bienroder Weg 54E, D-38108 Braunschweig, Germany, Tel.: +49 531 2155 577, Fax: +49 531 2155 900, E-mail:

References

[1] MicroChem, 1254 Chestnut Street, Newton, MA 02464, USA.Search in Google Scholar

[2] Gersteltec, Generale Guisan 26, 1009, Pully, Switzerland.Search in Google Scholar

[3] R.Feng, R.J.Farris: J. Micromech. Microeng.13 (2003) 80.10.1088/0960-1317/13/1/312Search in Google Scholar

[4] S.Shimizu, T.Yanagimoto, M.Sakai: J. Mater. Res.14 (1999) 4075.10.1557/JMR.1999.0550Search in Google Scholar

[5] M.R.VanLandingham, N.K.Chang, C.C.White, P.L.Drzal, S.H.Chang: J. Polm. Sci. B: Poly. Phys.43 (2005) 1794.10.1002/polb.20454Search in Google Scholar

[6] S.Yang, Y.-W.Zhang, K.Zeng: J. Appl. Phys.95 (2004) 3655.10.1063/1.1651341Search in Google Scholar

[7] K.I.Schiffmann: Int. J. Mater. Res.97 (2006) 1199.10.3139/146.101357Search in Google Scholar

[8] W.C.Oliver, G.M.Pharr: J. Mater. Res.7 (1992) 1564.10.1557/JMR.1992.1564Search in Google Scholar

[9] J.D.Ferry: Viscoelastic Properties of Polymers, 3rd ed., John Whiley & Sons, (1980), p. 96ff, p. 59, p. 411ff.Search in Google Scholar

Received: 2006-8-28
Accepted: 2007-2-6
Published Online: 2013-05-23
Published in Print: 2007-05-01

© 2007, Carl Hanser Verlag, München

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https://doi.org/10.3139/146.101485
Keywords for this article
SU8; Nanoindentation; Creep; Relaxation; Viscoelastic properties

Articles in the same Issue

  1. Contents
  2. Contents
  3. Editorial
  4. Editorial
  5. Basic
  6. Getting accurate nanoindentation data from time-dependent and microstructural effects of zinc
  7. Indentation-induced densification of soda-lime silicate glass
  8. Nanomechanical characterization of relaxation processes in As–S chalcogenide glasses
  9. Nanoindentation behavior and mechanical properties measurement of polymeric materials
  10. Model of a superlattice indentation
  11. Nanomechanical studies of MEMS structures
  12. Mechanical properties of nanostructured polymer particles for anisotropic conductive adhesives
  13. Nanomechanical studies of ultrathin polymeric resist films
  14. Testing the viscoelastic properties of SU8 photo resist thin films at different stages of processing by nanoindentation creep and stress relaxation
  15. Microscale characterization of bitumen – back-analysis of viscoelastic properties by means of nanoindentation
  16. Applied
  17. Visco-elastic properties of thin nylon films using multi-cycling nanoindentation
  18. Area function calibration in nanoindentation using the hardness instead of Young's modulus of fused silica as a reference value
  19. Multiscale modelling of nanoindentation
  20. Unusual architecture of the exceedingly tough Macadamia “nut”-shell as revealed by atomic force microscopy and nanomechanics
  21. Notifications
  22. DGM News
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