A photoacid generating (PAG) monomer containing a sulfonium group was synthesized and its polymerization behavior was investigated by conducting homopolymerization and copolymerization with various methacrylates found in chemically amplified photoresists. The PAG homopolymer itself acted as a high sensitivity negative resist. The PAG/methacrylates copolymers functioned as novel chemically amplified (CA) resists with PAGs incorporated in the polymer chain. Due to absence of phase separation, the resists exhibited excellent film formation behavior. Preliminary results have shown that acid generation efficiency remained almost the same regardless of remarkably differing components and compositions in the PAG/methacrylates copolymers. Finally, their imaging properties were investigated by exposure to 248 nm deep-ultraviolet (DUV) radiation.