Advertisement

Journal of Sol-Gel Science and Technology

, Volume 49, Issue 2, pp 233–237 | Cite as

Surface tension evolution during early stages of drying of sol–gel coatings

  • Dunbar P. BirnieIIIEmail author
  • David M. Kaz
  • Douglas J. Taylor
Original Paper

Abstract

Striation defects in spin-coated thin films have been blamed on unfavorable capillary forces that occur due to solvent evaporation commonly experienced during coating deposition. Solvent evaporation during spinning causes predictable composition changes at the surface and these can either stabilize or de-stabilize the surface with respect to convective motions within the coating solution. The present work examines the surface tension changes while adding the most volatile component rather than removing it. This is then a “reverse drying” process, but it provides us with the slope of the surface tension change during normal coating drying. We have examined coating solutions for a case where a specific solvent addition has previously been shown to prevent the formation of striation defects. By measuring both the starting solution (one that produces bad striation defects) and the co-solvent-modified solution (that produces much flatter coatings), we are able to demonstrate the correlation between surface tension changes during spinning and the striation defect formation (or prevention). For the present case, an aluminum-titanate sol–gel recipe, the solvent that eliminated the striation defects is also responsible for a continuous, gradual, reduction in surface tension during the spin-on process, consistent with a model proposed earlier (D. P. Birnie, J Mater Res 16:1145–1154, 2001).

Keywords

Spin coating Drying Surface tension Marangoni effect Sol–gel 

Notes

Acknowledgments

The support of the National Science Foundation under grant DMR 98-02334 is very warmly appreciated.

References

  1. 1.
    Birnie DP III (2001) Rational solvent selection strategies to combat striation formation during spin coating of thin films. J Mater Res 16(4):1145–1154. doi: 10.1557/JMR.2001.0158 CrossRefADSGoogle Scholar
  2. 2.
    Frasch P, Saremski KH (1982) Feature size in IC manufacturing. IBM J Res Develop 26(5):561–567CrossRefGoogle Scholar
  3. 3.
    Daniels BK, Szmanda CR, Templeton MK, Trefonas P III (1986) Surface tension effects in microlithography-striations in advances in resist technology and processing III. SPIE Proc 631:192–201Google Scholar
  4. 4.
    Du XM, Orignac X, Almeida RM (1995) Striation-free, spin-coated sol-gel optical films. J Am Ceram Soc 78:2254–2256. doi: 10.1111/j.1151-2916.1995.tb09079.x CrossRefGoogle Scholar
  5. 5.
    Kozuka H, Takenaka S, Kimura S (2001) Nanoscale radiative striations of sol-gel-derived spin-coating films. Scr Mater 44:1807–1811. doi: 10.1016/S1359-6462(01)00798-9 CrossRefGoogle Scholar
  6. 6.
    Bénard H (1900) Les tourbillons cellulaires dans une nappe liquide. Rev Gen Sci Pures Appl Bull Assoc Fr Av Sci 11:1261–1271Google Scholar
  7. 7.
    Bénard H (1927) Sur les tourbillons cellulaires et la theorie de Rayleigh. C R Acad Sci, Paris 185:1109–1111Google Scholar
  8. 8.
    Bénard H (1927) Sur les tourbillons en bandes et la theorie de Rayleigh. C R Acad Sci, Paris 185:1257–1259zbMATHGoogle Scholar
  9. 9.
    Block MJ (1956) Surface tension as the cause of Bénard cells and surface deformation in a liquid film. Nature 178:650–651. doi: 10.1038/178650a0 CrossRefADSGoogle Scholar
  10. 10.
    Pearson JRA (1958) On convection cells induced by surface tension. J Fluid Mech 4:489–500. doi: 10.1017/S0022112058000616 zbMATHCrossRefADSGoogle Scholar
  11. 11.
    Taylor DJ, Birnie DP III (2002) Striation prevention by targeted formulation adjustment: aluminum titanate sol–gel coatings. Chem Mater 14:1488–1492. doi: 10.1021/cm010192c CrossRefGoogle Scholar
  12. 12.
    Meyerhofer D (1978) Characteristics of resist films produced by spinning. J Appl Phys 49:3993–3997. doi: 10.1063/1.325357 CrossRefADSGoogle Scholar
  13. 13.
    Bornside DE, Macosko CW, Scriven LE (1987) On the modeling of spin coating. J Imaging Technol 13:122–130Google Scholar
  14. 14.
    Birnie DP III, Zelinski BJJ, Marvel SP, Melpolder SM, Roncone R (1992) Film/substrate/vacuum-chuck interactions during spin coating. Opt Eng 31:2012–2020. doi: 10.1117/12.59901 CrossRefADSGoogle Scholar
  15. 15.
    Birnie DP III, Zelinski BJJ, Perry DL (1995) Infrared observation of evaporative cooling during spin coating processes. Opt Eng 34:1782–1788. doi: 10.1117/12.203114 CrossRefADSGoogle Scholar
  16. 16.
    Haas DE, Birnie DP III (2002) Evaluation of thermocapillary driving forces in the development of striations during the spin coating process. J Mater Sci 37:2109–2116. doi: 10.1023/A:1015250120963 CrossRefGoogle Scholar
  17. 17.
    Haas DE, Birnie DP III (2001) Non-destructive measurement of striation defect spacing using laser diffraction. J Mater Res 16:3355–3360. doi: 10.1557/JMR.2001.0463 CrossRefADSGoogle Scholar
  18. 18.
    Cobb EC, Saunders OA (1956) Heat transfer from a rotating disk. Proc R Soc 236:343. doi: 10.1098/rspa.1956.0141 CrossRefGoogle Scholar
  19. 19.
    Kreith F, Taylor JH, Chong JP (1959) Heat and mass transfer from a rotating disk. J Heat Transf 81:95Google Scholar
  20. 20.
    Strawhecker KE, Kumar SK, Douglas JF, Karim A (2001) The critical role of solvent evaporation on the roughness of spin-cast polymer films. Macromolecules 34:4669–4672. doi: 10.1021/ma001440d CrossRefADSGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • Dunbar P. BirnieIII
    • 1
    Email author
  • David M. Kaz
    • 2
  • Douglas J. Taylor
    • 3
  1. 1.Department of Materials Science and EngineeringRutgers, The State University of New JerseyPiscatawayUSA
  2. 2.Graduate SchoolHarvard UniversityCambridgeUSA
  3. 3.TPL IncAlbuquerqueUSA

Personalised recommendations