Analysis of dissolution kinetics of narrow polydispersity poly(4-hydroxystyrene) in alkaline aqueous solution using machine learning

Abstract

Abstract Understanding the dissolution kinetics of resist materials is essential for their efficient development. In this study, we investigated the dissolution kinetics of poly(4-hydroxystyrene) (PHS) with a weight-average molecular weight (M w) of 8000–30 000 and a polydispersity index (M w /M n) of 1.07–1.20. The dissolution kinetics of PHS films was observed in tetramethylammonium hydroxide (TMAH) aqueous developers by a quartz crystal microbalance (QCM) method. The TMAH concentration was changed from 0 to 2.38 wt%. The formation of a thick transient swelling layer at these M w /M n values was suppressed compared with that at M w /M n > 2. QCM data were analyzed using the polynomial regression to clarify the effects of M w and M w /M n on the dissolution kinetics in a narrow polydispersity region. Both dissolving and swelling kinetics largely depended on M w/M n. M w had little effect in 2.38 wt% TMAH developer; however, it had a large effect on the swelling when 2.38 wt% TMAH developer was diluted.