| Anionic Polymerization |
| Acrylates |
| Acrylate polymers have been used extensively in 193 nm photoresist
designs due to their facile functionalization and favorable polymerization
characteristics(1). Unfortunately, the p-system in these polymers
contributes a large amount of absorbance at 157 nm and effectively precludes
their use at this wavelength. However, our research group has recently shown the absorbance of these
materials can also be significantly decreased through the addition of
electron-withdrawing substituents(2). For example, poly(methyl trifluoromethacrylate) was prepared from the
commercially available acid(3), and polymerized according to literature
procedures(4). |
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| The absorbance spectrum of the final homopolymer is displayed below,
showing that this material has an absorbance of ~3 / mm,
less than half that of PMMA. |
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| To confirm that the favorable imaging characteristics of acrylates
has not been adversely affected, poly(tert-butyl trifluoromethacrylate)
was prepared(5) and is undergoing preliminary imaging experiments. |
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| Although the results from these experiments will give some
indication of the potential performance available from this class of materials,
a candidate for an actual photoresist polymer will most likely have to follow a
model similar to that described for acrylates as 193 nm photoresists(1). To that end, we are in the process of
preparing the acrylate ter- and tetrapolymers shown below to determine their imaging potential. |
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| R=Fluorinated alicyclic unit for etch-resistance
(see etch resistance section) |
| References: |
| 1) Allen, R. D., Wan, I. Y., Wallraff, G. M., DiPietro, R. A., Hofer, D. C., Kunz, R. R. “Microelectronics Technology;
Polymers for Advanced Imaging and Packaging” American Chemical Soceity, Washington D.C., 1995, Ch. 17. |
| 2)Conley, Will Presentation, International Symposium on 157nm Lithography, Dana Point, California, 2000. |
| 3) C. Botteghi, C. Lando, U. Matteoli, S. Paganelli, G. Menchi, J. Fluorine Chem. 1997, 83(1), 67 |
| 4)H Ito, ACS Symposium Series 696, “Application of anionic polymerization research” 1996, 218. |
| 5)A. L. McCloskey, G. S. Fonken, R. W. Klüber, W. S. Johnson, Org. Synth. Coll. Vol. IV, 1963, 261
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2nd Annual Symposium on 157 nm Lithography: UT Poster on Acrylates
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| Version History |
| Original page created 01/30/01 |
