Synthesis and Characterization of Some Acrylate Copolymers and their Evaluation as Aqueous Developable Photoresists

摘要

In the recent past,it has been found that the use of onium salts as acid-generating species has improved the performance of photoresists,particularly for microelectronic applications.However,little research has been dedicated to the use of these photo-initiators in aqueous-developable resists.This work describes the synthesis and characterization of some water-soluble polymers and investigates the feasibility of employing one of the onium salts in the formulation of a resist polymer for use in aqueous conditions.The ability of this onium salt to photo-initiate the cationic polymerization of epoxies residues was exploited using water-soluble copolymers,containing glycidyl methacrylate (GMA).The comonomers included methacrylic acid.Various copolymers were prepared by radical copolymerization typically in methyl ethyl ketone.It was found that the copolymer containing 85 mol.% of GMA unit in feed was soluble in aqueous base and crosslinked in the presence of photogenerated acid caused by acid-initiated ring opening polymerization of the pendant epoxide groups.A good pattern with reasonable resolution was attained by exposure to a UV lamp with 1=365 nm light followed by a post exposure bake at 80°C for 1 min.