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Silica Aerogel: An Intrinsically Low Dielectric Constant Material

Published online by Cambridge University Press:  15 February 2011

Lawrence W. Hrubesh*
Affiliation:
Chemistry and Material Science Department, Lawrence Livermore National Laboratory, Box 808, Livermore, California 94550
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Abstract

Silica aerogels are highly porous solids having unique morphologies in which both the pores and particles have sizes less than the wavelength of visible light. This fine nanostructure modifies the normal transport mechanisms within aerogels and endows them with a variety of exceptional physical properties. For example, aerogels have the lowest measured thermal conductivity and dielectric constant for any solid material. The intrinsically low dielectric properties of silica aerogels are the direct result of the extremely high achievable porosities, which are controllable over a range from 75% to more than 99.8%, and which result in measured dielectric constants from 2.0 to less than 1.01. This paper discusses the synthesis of silica aerogels, processing them as thin films, and characterizing their dielectric properties. Existing data and other physical characteristics of bulk aerogels (e.g., thermal stablity, thermal expansion, moisture adsorption, modulus, dielectric strength, etc.), which are useful for evaluating them as potential dielectrics for microelectronics, are also given.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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References

1. Hippel, A.R. von, Dielectric and Waves, (J. Wiley and Sons, New York, 1954), p. 28.Google Scholar
2. Hrubesh, L.W., Keene, L.E., and Latorre, V.R., J. Mater. Res. 8, 1736 (1993).Google Scholar
3. Brinker, C.J. and Scherer, G.W., Sol-Gel Science (Academic Press, N.Y., 1990) p. 97.Google Scholar
4. Prakash, S.S., Brinker, C.J., Hurd, A.J. and Rao, S.M., in Advances in Porous Materials, edited by Komameni, S., Smith, D.M., and Beck, J.S., (Mat. Res. Soc. Symp. Proc., Vol.371, Mat. Res. Soc., Pittsburgh, 1995) pp. 205210.Google Scholar
5. Smith, D.M., Anderson, J., Cho, C.C., and Gnade, B.E., in Advances in Porous Materials, edited by Komarneni, S., Smith, D.M., and Beck, J.S. (Mat. Res. Soc. Symp. Proc., Vol. 371, Mat. Res. Soc., Pittsburgh, 1995) pp. 261266.Google Scholar
6. Hrubesh, L.W. and Poco, J.F., in Advances in Porous Materials, edited by Komarneni, S., Smith, D.M., and Beck, J.S., (Mat. Res. Soc. Symp. Proc., Vol.371, Mat. Res. Soc., Pittsburgh, 1995) pp. 195204.Google Scholar
7. Hrubesh, L.W. and Poco, J.F., J. Non-Cryst. Solids, (to be published).Google Scholar
8. daSilva, A., dosSantos, D.I., and Aegerter, M.A., J. Non-Cryst. Solids 96, 11591166 (1987).Google Scholar
9. Brüesch, P., Stucki, F., Baumann, Th., Kluge-Weiss, P., Brühl, B., Niemeyer, L., Strümpler, R., Zeigler, B. and Mielke, M., J. Appl Phys. A, 57, 329337 (1993).Google Scholar
10. Yarbrough, W.A., Guruaja, T.R., and Cross, L.E., Am. Ceram. Soc. Bull. 66, 692 (1987).Google Scholar
11. Cao, W., Gerhardt, R., and Wachtman, J.B., in Advances in Ceramics, edited by Yan, M.F., Niwa, K., H. Obryan, Jr. and Young, W.S. (Amer. Ceram. Soc., Ohio, 1989), pp. 409418.Google Scholar
12. Henning, S. and Svensson, L., Phys. Scripta 23, 697 (1981).Google Scholar
13. Krevelen, D.W. Van, Properties of Polymers, (Elsevier, New York, 1990), pp. 330333.Google Scholar
14. Fricke, J. and Emmerling, A., in Chemistry, Spectroscopy, and Applications of Sol-Gel Glasses, edited by Reisfeld, R. and Jorgensen, C.K., (Springer Series on Structure and Bonding, Vol.77, Springer-Verlag, Heidelberg, Germany, 1991) p. 37.Google Scholar