The thin film formation of spin coating is one of the important factors in the fabrication of micro-electronic devices. In this study, the theoretical models for thickness variation during spin coating are discussed and the nanotopography impact is analyzed. The finite-difference-time-domain method and the finite element method are used to solve the convective diffusion equation for the solvent distribution and the Navier-Stokes equation including solvent evaporation for the film thickness change. These numerical calculations have good agreement to the experimental results of the non-chemically amplified resist (CAR) and the CAR. Solvent distributions of non-spin coating are described through the mesoscale modeling by using the Monte Carlo method. How the nanotopography impacts on the variation of resist distribution after spin coating is investigated quantitatively. So, the reason of the similarity in the transfer functions of the different type wafers is the solvent diffusion and evaporation.