The film formation dynamics in spin coating

Abstract

Thin film formation using the process of spin coating is investigated. The liquid film and surrounding gas phase two-dimensional (2-D) full governing equations with applicable boundary conditions are formulated. The heat and mass transfer that occurs in the gas and liquid phase and across the free surface, including the evaporation of solvent, are taken into account. The governing equations and boundary conditions are then reduced to a 1-D case based on the variables radial dependency. The detailed film formation process that commences at the start of the spinning and ends with the dry-up of the coated film is numerically simulated by utilizing the 1-D governing equations. The complex effects of various process parameters, e.g., spinning speed, initial solute concentration, and disk heating, are clarified by the present numerical analysis. It was found that the final film thickness is mainly determined at the time when the film thinning rate resulting from radial convection has the same order as the film thinning rate resulting from solvent evaporation.