Novel ArF photoresist polymer to suppress the formation of roughness in plasma etching processes

Abstract

The most serious problem associated with 193 nm lithography using ArF photoresists is the formation of roughness on photoresist film during plasma processes. The main determining factor for the formation of roughness during plasma etching is a chemical reaction between the photoresist polymer and reactive species from the plasma. The lactone group in photoresist polymer is highly chemically reactive, and shrinking the lactone structure enhances the formation of roughness. The authors propose a novel ArF photoresist polymer on the basis of the mechanism for the formation of roughness. The formation of roughness was suppressed much more in the novel photoresist polymer than that in the previous type. Chemical reactions in the novel photoresist polymer were evenly spread on the photoresist film surface by adding a polar structure. As a result, decreases in the lactone group were inhibited, which led to ArF photoresist roughness being suppressed.