Synthesis of novel copolymer based on precipitation polymerization and its application in positive-tone photoresist

A series of copolymers Poly (TBA-CA-St-ASM)(PTCSA) were synthesized via precipitation polymerization by using tert-Butyl acrylate (TBA), Styrene (St), p-acetoxy styrene (ASM), and cedryl methacrylate (CA) as co-monomer. Then, Poly (TBA-CA-St-HS)(PTCSH) was prepared in the presence of sodium methoxide in methanol. The fourier transfer infrared (FT-IR) spectra and proton nuclear magnetic resonance (¹H–NMR) spectra indicated that the synthesis was successful. The molecular weight, glass transition temperature (T_g) and thermal decomposition temperature (T(10%)) of the copolymers increased with the addition of CA. Moreover, a positive-tone chemically amplified Krypton Fluoride (KrF) photoresist was prepared, and the photolithography performance of the photoresist was evaluated using a KrF laser exposure system, the result showed that the resolution could reach the level of 0.25 μm.