Acid-catalyzed single-layer resists for ArF lithography

A positive-tone single-layer resist for use with 193-nm radiation has been developed. The system contains a terpolymer of methyl methacrylate, methacrylic acid, and t-butyl methacrylate, along with a photoacid generator. The chemically amplified deprotection of the t-butyl methacrylate into methacrylic acid increases the polarity of the resist and allows selective dissolution in metal-ion-free aqueous base solutions. The resist sensitivity is less than 10 mJ/cm2, and its inherent resolution is better than 0. 1 m. These acrylate-based systems have potential for both lower cost and better environmental stability compared with the deep ultraviolet chemically amplified resists which use phenolic resins.