A new model for photoresist-polymer dissolution in aqueous base is presented combining the critical ionization model [P. C. Tsiartas et al.: Macromolecules 30 (1992) 4656] and the percolation model [A. Reiser et al.: Angew. Chem., Int. Ed. 35 (1996) 2428]. The dependence of dissolution rate on molecular weight and hydrophilic fraction of the polymer has been studied using the new model, as well as the “gel” layer thickness formed during dissolution. The new model predicts available experimental data, and can be a basis for line-edge roughness predictions.

The morphology of photoresist polymer surfaces fabricated by lithographic processes is shown to exhibit self-affine behavior for a specific range of scales. The roughness parameters appropriate for the characterization of self-affine surfaces (surface width w, correlation length ξ and roughness exponent α) are found to depend on the exposure dose (i.e. the solubility) involved in the lithography process and to be correlated. A similar dependence and correlation is extracted from a Monte-Carlo simulation of polymer dissolution, thus indicating the pronounced contribution of the dissolution process to the formation of lithographic roughness. The self-affinity and the correlated behavior of the roughness parameters is a general phenomenon for dissolving polymers of varying solubility and not limited to the lithographic process.