Properties of Photoresist Polymers


This chapter is intended to provide physical property data of photoresist polymers. Photoresist materials and lithographic patterning process are described. Optical properties of a photoresist are determined by its base polymer as well as additives in the photoresist system, such as photoactive compounds, dissolution inhibitors, etc. Proper dissolution of photoresist polymers in aqueous base solutions, usually 0.263N aqueous tetramethylammonium hydroxide (TMAH) solution, is critical to achieving good resist performance. The dissolution rate of photoresist polymers depends on various parameters, including polymer type, molecular weight, copolymer composition, interactions with additives in the polymers, as well as temperature and base strength. The dissolution rates of photoresist and polymers can also be regulated by making miscible blends of two or more polymers. The dissolution rates of photoresist polymers can be further modulated by additives, such as photoacid generators (PAG) or dissolution inhibitors. The photoacid generators are generally hydrophobic due to their usually bulky chromophores. Therefore, they generally act as to slow down the dissolution of photoresist polymers in aqueous base solutions, a phenomenon called dissolution inhibition. Superior reactive ion (plasma) etch resistance of photoresist polymers is crucial to ensuring faithful transfer of the photoresist images into the appropriate substrates. Phenomenological parameters have been proposed to correlate the etch rates of a photoresist polymer to its composition. One such empirical parameter is Ohnishi parameter, the other is ring parameter. Correlations of these parameters with experiment results suggest that incorporating more carbon atoms, particularly in a ring form, would enhance etch resistance.

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Properties of Photoresist Polymers
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Physical Properties of Polymers Handbook
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  • James E. Mark Send Email (1)
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  • 1 Department of Chemistry, University of Cincinnati, Crosley Tower, Martin Luther King Drive, 45221-0172, Cincinnati, OH
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  • Qinghuang Lin Send Email (2)
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  • 2 IBM Thomas J. Watson Research Center, 1101 Kitchawan Rd, Route 134, 218, 10598, Yorktown Heights, NY
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