Photoresist Processing Trouble-Shooting Etchants and Solvents
Photoresists Ancillaries Storage/Handling/Ageing Substrate Pre-Treatment and Coating Baking Steps Exposure Development Coating and Lift-off Etching and Stripping
Mechanism Development Rate and Dark Erosion Impact of the Softbake Impact of the Exposure Dose
The carboxylic acid formed during exposure moves from the hydrophobic to the hydrophilic part of the cresol chain and promotes the deprotonisation of the OH-group increasing the resist solubility in aqueous alkaline developers.

Beside the carboxylic acid, also acetic acid (formed by alkaline developers from the resist solvent PGMEA) increases the development rate of exposed and unexposed resist. This explains the higher dark erosion of resist with a remaining solvent concentration too high (e.g. in case of an insufficient softbake).
Weiterführendes Dokument (pdf) Literature: Exposure and Development  The Photoreaction  Softbake and Remaining Solvent Concentration
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