A series of novel ionic photo-acid generators (PAGs) useful in chemically amplified photoresist formulations has been developed, which are salts comprising a photoactive triphenyl cation and a sulfonylimide anion containing an aromatic group. A styrene-based polymer resin is prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization and blended with the novel PAGs as deep ultraviolet (DUV) photoresists. Furthermore, one of the novel PAGs is used as a monomer to be bound into the polymer resin through RAFT polymerization to obtain a photoresist-PAG copolymer. The prepared photoresists are exposed by a DUV light to study their sensitivity, acid diffusion length, and lithography pattern profile. The results show that both the photoresists blended with the novel PAGs and the photoresist-PAG copolymer exhibit good resistance to acid diffusion and low line sidewall roughness (LSR).
Yue Liu,Dong Wang,Haihua Wang,Huan Chen,Qianqian Wang,Wenbing Kang
The inherent acid diffusion during post-exposure baking poses significant challenges in balancing resolution, line-edge roughness, and sensitivity (RLS), thereby constraining the performance of chemically amplified photoresists (CARs) in advanced lithography. This study introduces a novel series of alkene-functionalized imino/imido benzenesulfonate photoacid generators (PAGs), characterized by their solubility, thermal stability, and polymerization attributes. These derivatives can copolymerize with acrylates and methacrylates to form PAG-bound copolymers, integrating non-ionic PAG units and acid-cleavable bulky alicyclic substituents, facilitating their use as “single-component” resists devoid of additives. Upon exposure to electron beams or ultraviolet radiation, the sulfonamide esters undergo N─O bond scission, producing photoacids that catalyze the deprotection of acidolytic groups. Compared to PAG-blended systems, these PAG-bound systems curtail acid diffusion by generating long-chain sulfonic acids, while preserving high sensitivity. The formulated single-component CARs demonstrate superior resolution and roughness, achieving a minimum linewidth of 42 nm at an electron beam dose of 73 µC cm − 2 . This research provides a rational design for polymerizable imino/imido benzenesulfonate PAGs and single-component CARs, offering a viable solution to the RLS problem.
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