Intrinsically photosensitive polyimide photoresist and its double crosslinking mechanism

A new negative-working photoinitiator-free polyimide was developed for photolithographic processes. The polyimide introduced a photosensitive benzophenone unit into the backbone and a cross-linking group (methacrylate) into the side chains. A novel pre-functionalized diamine monomer was designed to avoid using corrosive sulfonyl chloride in the polyimide side-chain introduction step. Mechanistic studies revealed that benzophenone initiates various cross-linking reactions under i-line (UV 365 nm) irradiation, resulting in excellent photolithography performance of polyimide, with a resolution of 10 μm.