Dissolution rate analysis of ArF resists based on the percolation model

We investigated the dissolution properties of ArF-resist base polymers and ArF resist in order to study their development mechanism. We measured the dissolution rate of methacrylate copolymers and a resist as a function of the hydrophilic unit content, and simulated dissolution phenomena by using percolation theory. The obtained dissolution-rate curves had strong nonlinear dependence on hydrophilic unit content. In the simulation analysis, base molecule diffusion through the hydrophilic path was modeled as particle diffusion through the percolation field. The diffusion constant was calculated by using conventional and modified diffusion models. We suggest a new variable to describe diffusion-path width in the modified model. The simulation results indicate that our model reproduced the experimental results better than the conventional model.