The serious problem associated with 193-nm lithography using an ArF photoresist is roughness formation of photoresist polymer during plasma processes. We have previously investigated the mechanism of roughness formation caused by plasma. The main deciding factor for roughness formation is a chemical reaction between photoresist polymer and reactive species from plasma. The lactone group in photoresist polymer is highly chemically reactive, and shrinking the lactone structure enhances the roughness formation. In this paper, on the basis of the mechanism of roughness formation, we propose a novel ArF photoresist polymer. The roughness formation was much more suppressed in the novel photoresist polymer during plasma etching process than in the previous type. In the novel photoresist polymer, chemical reactions were spread evenly on the photoresist film surface by adding the polar structure. As a result, decreases in the lactone group were inhibited, leading to suppressing ArF photoresist roughness.