Relationship between poly(4-hydroxystyrene) (PHS) and tetramethylammonium hydroxide (TMAH) concentrations during the development of PHS films in TMAH aqueous solution studied by a quartz crystal microbalance (QCM) method

Abstract

Abstract Development (the dissolution of resist films in developer) is an important lithographic process. However, details of the dissolution of resist polymers remain unclarified. In this study, the viscosity of 2.38 wt% tetramethylammonium hydroxide (TMAH) aqueous solution with poly(4-hydroxystyrene) (PHS) was investigated using a quartz crystal microbalance method. The relationship between PHS concentration and the viscosity of 2.38 wt% TMAH aqueous solution with PHS was measured. The kinetics (temporal change) of viscosity and PHS concentration during development was clarified. The maximum PHS concentration achievable during development approximately corresponded to the TMAH concentration independently of the film thickness.