Analysis of dissolution kinetics of poly(4-hydroxystyrene) with different molecular weight distributions in alkaline aqueous solution using machine learning

Photoresists have been widely used as patterning materials for electric devices such as displays and semiconductor. Understanding pattern formation mechanism is essential for the efficient development of resist materials. In this study, we investigated the dissolution kinetics of poly(4-hydroxystyrene) (PHS) with weight-average molecular weights (Mw) of 9000-30000 and molecular weight distribution (Mw/Mn) of 1.07-1.20. The dissolution kinetics of PHS films was observed in tetramethylammonium hydroxide (TMAH) aqueous developers using a quartz crystal microbalance (QCM) method. The TMAH concentration was changed from 0 to 2.38 wt%. The obtained data were analyzed using polynomial regression to clarify the effects of Mw and Mw/Mn on the dissolution kinetics of PHS films. From the results of analysis, both dissolving and swelling behavior largely depended on Mw/Mn. Mw had a little effect on the dissolving, and however, had a large effect on the swelling in dilute TMAH aqueous solution.