Cyclization Reaction in Acrylonitrile-Contained Acrylic Copolymers and Its Possible Application for the Improvement of Dry Etch Resistance for Photoresists.

Abstract

Acrylonitrile (AN)/methacrylic acid (MAA) copolymer and AN/tert-butyl methacrylate (tBMA)/MAA terpolymer were prepared, and their dry etch resistance were measured The excellent dry etch resistance found in these materials were attributed to the contribution of some induced chemical reactions. To further understand their roles in the improvement of dry etch resistance, the reactions especially the thermally induced cyclization reaction were investigated in detail. It was found that thermally induced cyclization of the nitrile groups in carboxyl acid-contained copolymers closely depended on the content of the acidic component. Protection of the acid moiety through esterfication thus suppressed the occurrence of the reaction. Conversely, cleavage of the protection groups led to the resumption of the reaction. Attempt was made to correlate the increase of fry etch resistance upon thermal treatment with the formation of cyclized structures.