The phenomena involved in positive chemically amplified resists are the result of intricate chemical and physical mechanisms. This complexity is observed from spin-coating to development. The physical properties of the lithographic layer are strongly influenced by the chemistry used. In turn, the deprotection reaction can exhibit different kinetics depending on the physical properties and thermal history of the film. The deprotection reaction generates an expanded matrix that can collapse and densify when the PEB temperature is higher than the transition temperature. This work shows that both deprotection and dissolution rate are not related to exposure dose by simple relationships. This new approach provides a deeper understanding for good control, design and modeling of these systems.