Characterization and Lithographic Application of Calix[4]resorcinarene Derivatives

Calix[4]resorcinarenes were prepared by the condensation of resorcinol and aldehydes (acetaldehyde, benzaldehyde, and 4-isopropylbenzaldehyde), and two isomers, C 4v (ccc) and C 2v (ctt), were separated by fractional crystallization. The products were characterized by NMR and FTIR, and their dissolution rate in aqueous base was measured. The eight hydroxyl groups of the calix[4]resorcinarenes were protected with acid labile t-butoxycarbonyl and t-butoxycarbonylmethyl. The protected calixarenes were thoroughly characterized by differential scanning calorimetry, FTIR, and variable-temperature 1H and 13C NMR. Their interaction with 4-isopropylphenol through hydrogen bonding was investigated by 13C NMR and correlated with their inhibition effect of dissolution of poly(4-hydroxystyrene-co-t-butyl acrylate) in an aqueous base, as studied by quartz crystal microbalance. Finally, the protected calixarenes were employed as a dissolution inhibitor of polyhydroxystyrene-based deep UV and electron beam chemical amplification resists to improve their contrast and performance.