Dissolution kinetics of polymer films in <i>n</i>-butyl acetate developer investigated by quartz crystal microbalance method

Abstract A typical chemically amplified resist relies on the polarity change of the resist polymer to achieve dissolution contrast, with negative-tone development being a critical technology for these resists. This study investigated the dissolution kinetics of polymer films in n -butyl acetate, a common developer for negative-tone imaging, using the quartz crystal microbalance (QCM) method. The examined polymers included poly(4-hydroxystyrene) (PHS), whose hydroxyl groups are partially protected by t -butoxycarbonyl groups, in addition to polymethylmethacrylate and polystyrene. The diffusion constants and hydrodynamic radii of the polymers during development were estimated by analyzing the obtained QCM charts using the diffusion equation. The hydrodynamic radii of the polymers were estimated to be 0.23–10.6 nm. Notably, the hydrodynamic radius of PHS during development in n -butyl acetate was larger than that observed in a 2.38 wt% tetramethylammonium hydroxide aqueous solution (a standard developer for the positive-tone imaging).