Synthesis of Narrow Molecular Weight Distribution Copolymers for ArF Photoresist Materials by Nitroxide Mediated Polymerization

摘要

ArF candidate photoresist polymers have been synthesized by nitroxide mediated polymerization (NMP). Statistical copolymerizations of a-gamma butyrolactone methacrylate, 3-hydroxy-1-adamantyl methacrylate, and 2-methyl 2-adamantyl methacrylate with 5-10 mol% of controlling comonomers (i.e., styrene, p-acetoxystyrene, 2-vinyl naphthalene, acrylonitrile, and pentafluorostyrene), which are necessary for controlled polymerization of methacrylates by NMP with the unimolecular alkoxyamine initiator BlocBuilder, have been used. As little as 5 mol% controlling comonomer in the feed is demonstrated to be sufficient to produce linear evolution of number average molecular weight against conversion (X) up to X = 0.7 for relatively low target degrees of polymerization. All of the resulting copolymers have relatively low dispersities ((M) over bar (w)/(M) over bar (n) approximate to 1.4) and show relatively low absorbance at 193 nm, comparable to other 193 nm candidate photoresists reported previously, with the exception of VN-containing copolymer.