Modified model of drying process of a polymer liquid film taking effects of latent heat and heat conductivity into account

Abstract

In Photomask Japan 2002 we reported a model of coating and drying process for the flat polymer (resist) film fabrication. The model models the process that polymer solution coated on a flat substrate by scanning technique, which is developed for LSI technologies at the next generation, is dried under reduced pressure. After above drying process, a resist film having a typical thickness profile that the edge of the film is thicker and just the region next to the edge's bump is thinner. Using the model, we numerically clarified the bumpy structure of the edge of a resist film depended on some essential parameters -- vaporization rate, diffusion coefficients coated solution thickness, intrinsic viscosity and so on. But the former model doesn't include the effects of a drop of temperature on the surface of a liquid film and the inside of it by latent heat and diffusion of heat by conductivity. But we cannot ignore these effects since a drop of temperature is essential in phase transition. And change of diffusion coefficients and viscosity by the drop of temperature has an important influence on the model. In this paper, we will report the modified model taking a drop of temperature on the surface of a liquid film and the inside of it by latent heat and diffusion of heat by conductivity and change of diffusion coefficients and viscosity by it into consideration and numerical results using the model.