We combine such experimental analysis with simulation of the kinetic of dissolution using in-house software tools. The general kinetic model is depicted below. The solubility switch is an adaptation of the Critical Ionizaton model^1-3; in this adaptation, aqueous base penetrates the polymer film, polymer sites are reversible deprotonated by hydroxide ion, and once a critical number of polymer sites are ionized the chain is surrounded by water and dissolved.

Such simulations predict structure and composition as a function of time following immersion in developer. As an exmaple, Predictions of how film dissolution is affected by the relative rate of deprotonation of the polymer for a specific set of conditions is shown below. Depending on the deprotonation rate, film dissolution can occur by (left to right) full swelling of the entire film, formation of a significant but distinct interfacial layer, or surface-limited dissolution akin to the etching of metals.

 References

1. P. C. Tsiartis, et al Macromolecules 30, 4656 (1997).
2. L. W. Flanagin, et al Macromolecules 32, 5337 (1999).
3. F. A. Houle, et al, Macromolecules 35, 8591 (2002).