Preparation and characterization of UV-curable copolymers containing alkali soluble carboxyl pendant for negative photoresist

tert -Butyl acrylate (TBA), benzyl methacrylate (BzMA) and acrylic acid (AA) were used to synthesize prepolymer (PTBA) with carboxyl pendant through free-radical polymerization. Glycidyl methacrylate (GMA) was then added to react with carboxylic acid group of PTBA to form UV-curable copolymer PTBA-G. Proton Nuclear magnetic resonance ( 1 H NMR) and Fourier transform infrared spectroscopy (FTIR) were used to confirm the structure and functional group of prepolymer and copolymer, GPC was employed to determine the molecular weight and polydispersity. Real-time infrared and photo differential scanning calorimetry (photo-DSC) were used to evaluate the UV-curable kinetics of copolymer, thermo-gravimetric analysis (TGA) showed the thermal stability of the copolymers increased as the GMA content increase. When the ratio of GMA and AA was 0.3, it showed excellent resolution of 50 μm by SEM observation.