Dependence of photoresist dissolution dynamics in alkaline developers on alkyl chain length of tetraalkylammonium hydroxide

Abstract Extreme ultraviolet (EUV) lithography is already being applied to the high-volume manufacturing of semiconductor devices. Although EUV lithography has enabled fine pitch scaling, such sub-20 nm order fabrication has also imposed the issue of stochastic defects (in the form of randomly generated line bridges and breaks). To resolve such an issue, understanding the development process is essential. In this study, the dissolution dynamics of three types of EUV photoresist were investigated for four types of alkaline developer using a quartz crystal microbalance method to clarify the swelling and dissolution kinetics during photoresist development. In experiments, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), and tetrabutylammonium hydroxide (TBAH) aqueous solutions were used as developers. Poly(4-hydroxystyrene) (PHS)-type, acryl-type, and hybrid-type photoresists were examined. The effect of the alkyl chain length of tetraalkylammonium cations depended on the type of photoresist. The dissolution dynamics depended on the combination of types of photoresist and developer.