Novel photoresist design based on electrophilic aromatic substitution |
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Authors: | B Reck R D Allen R J Twieg C G Willson S Matuszczak H D H Stover N H Li J M J Frchet |
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Affiliation: | B. Reck,R. D. Allen,R. J. Twieg,C. G. Willson,S. Matuszczak,H. D. H. Stover,N. H. Li,J. M. J. Fréchet |
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Abstract: | A new approach to resist materials that exhibit chemical amplification is based on systems comprised of three structural units at least one of which is polymeric: (a) an aromatic moiety such as poly(4-hydroxystyrene), Novolac, or other aromatic compounds which are susceptible to electrophilic aromatic substitution; (b) a latent electrophile which may be polyfunctional and, in the case of this study, is a carbocation precursor; (c) a material which generates strong acid upon irradiation. Exposure of a film containing these three structural components affords a latent image of acid dispersed in the polymer matrix. In a subsequent baking step, the photogenerated acid reacts with the latent electrophile releasing a very reactive carbocationic species which becomes bound to the aromatic moiety. As one of the components of the resist is polymeric and multifunctional, the result is a rapid increase in molecular weight due to branching and crosslinking of the chains. In terms of imaging, this process translates into the formation of a negative image of the mask although under some conditions a positive image may also be produced. The system shows a very high sensitivity and can provide high resolution images devoid of distortion due to the absence of swelling during development. |
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