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 (tau) -butyl methacrylate, along with a photoacid generator. The chemically amplified deprotection of the (tau) -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 micrometers . 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.