Stereo-Selective Synthesis of exo-Norbornene Derivatives for Resist Materials

• Published in: Journal of Photopolymer Science and Technology Vol. 22; no. 3; pp. 365 - 370
• Main Authors: Kanao, Miki, Otake, Atsushi, Tsuchiya, Kousuke, Ogino, Kenji
• Format: Journal Article
• Language: English
• Published: Hiratsuka The Society of Photopolymer Science and Technology(SPST) 01.01.2009; Japan Science and Technology Agency
• Subjects: 193 nm lithography; 2-substituted norbornene; Copolymers; Derivatives; Diels-Alder reactions; Isomerization; Isomers; maleic anhydride; Nuclear magnetic resonance; Purification; random copolymer; Resists; stereo-selective synthesis
• ISSN: 0914-9244; 1349-6336; 1349-6336
• DOI: 10.2494/photopolymer.22.365

In this paper, simple, effective, and stereo-selective syntheses of 5-norbornene-2-carboxylic acid (NBCA) and its derivatives were reported. The properties as a resist material were also investigated. In order to obtain exo-rich isomer at high yield, methyl 5-norbornene-2-carboxylate (MNBC) was synthesized via Diels-Alder reaction as a starting material at first. Then, the isomerization and exo-selective hydrolysis of MNBC were performed in a basic condition to synthesize exo-rich NBCA. Exo-rich t-butyl 5-norbornene-2-carboxylate (tBNBC) was prepared by non-selective esterification. After purification, exo-tBNBC was isolated. The random copolymers consisting of exo- or endo-rich tBNBC (endo-rich tBNBC was synthesized by classic Diels-Alder reaction) and maleic anhydride were synthesized as resist materials via free radical polymerization. The resulting copolymers were characterized by GPC and 1H NMR. Furthermore, the acidic deprotection behavior of exo- and endo-tBNBC was monitored using 1H NMR for the model reaction of resist system. In this study, it is suggested that the endo/exo ratio of norbornene derivatives affect reactivity, rate of reaction, property of polymer and monomer, and lithographic performance.