Synthesis of ArF photoresist polymers via continuous-flow RAFT polymerization with an efficient strategy for their thiocarbonylthio end group removal

Photoresists are critical materials for patterning high-resolution features in semiconductor manufacturing. ArF photoresist polymers, which are predominantly multicomponent acrylate copolymers, cannot be synthesized via living anionic polymerization. Consequently, conventional free radical polymerization (FRP) remains the predominant method for their production. However, FRP struggles to meet the stringent requirements for high-performance photoresists, which demand well-defined molecular weights, narrow polydispersity ( Đ ), and excellent batch-to-batch consistency. Herein, we report a robust synthesis of ArF photoresist polymers by integrating continuous-flow technology with reversible addition–fragmentation chain transfer (RAFT) polymerization. This process maintains high output quality stability and controllability, yielding polymers with well-defined molecular weights and narrow polydispersity ( Đ < 1.2). It achieves over 90 % conversion within 200 min and is applicable to microchannel systems with solids content exceeding 40 wt%, meeting commercially viable polymerization results. Furthermore, we introduce an efficient and green method for removing thiocarbonylthio end groups via aqueous hydrogen peroxide treatment under mild conditions. This approach prevents the degradation of thermal stability and lithographic sensitivity performance typically caused by residual RAFT terminal groups. The RAFT-derived, desulfurized photoresist produced patterns with significantly lower line-edge roughness than the FRP-based material, demonstrating superior lithographic performance. This end group removal strategy offers high throughput, excellent efficiency, and seamless compatibility with continuous-flow processes, highlighting its strong potential for industrial adoption.