Acrylic resins with oxetane pendant groups for free radical and cationic dual-curing photoresists

Photoresists play an important role in the electronic information industry; however, traditional photoresists have disadvantages including severe volume shrinkage, low precision, and poor adhesion. Here, a combined free radical / cationic dual-curing dry film photoresists (DFRs) for 405 nm photolithography was developed based on functional acrylic resins containing oxetane pendant groups. The acrylic resins were successfully synthesized by free radical copolymerization of methyl methacrylate, methacrylic acid, ethyl methacrylate and 3-ethyl-3-(methacryloyloxy)methyloxetane. The structure and properties of resins were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis. The resins could undergo cationic photopolymerization to generate a film with good mechanical and thermal properties. Notably, the prepared DFRs showed excellent comprehensive performances including outstanding pattern transfer ability with a high resolution of 20 μm, high photosensitivity, high contrast, satisfactory developing speed, and good adhesion to the substrate. Such oxetane-containing acrylic resins may have potential application in high-performance DFRs.