Adhesion-promoted copolymers based on norbornene derivatives and maleic anhydride for 193-nm photoresists

A copolymer of t-butyl 5-norbornene-2-carboxylate, 2-(2-methoxyethoxy)ethyl 5-norbornene-2-carboxylate, norbornene, and maleic anhydride was synthesized as a matrix polymer for ArF excimer laser lithography. Hydrophilic 2-(2-methoxyethoxy)ethyl ester groups are introduced into side chains of the matrix polymer in order to improve adhesion to a silicon substrate without causing cross-linking during a lithographic process. The resist formulated with the polymer shows better adhesion to a silicon substrate as the mole fraction of 2-(2-methoxyethoxy)ethyl 5-norbornene-2-carboxylate increases. 0.15 mu m line and space patterns were obtained at a dose of 10.5 mJ cm(-2) using an ArF excimer laser stepper. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.