Analysis of drying shrinkage and flow due to surface tension of spin-coated films on topographic substrates

In semiconductor manufacturing processes, it is important that the SiO₂ isolation films around aluminum connection lines have flat surfaces in order to produce the multilayered connection lines used in high-density devices. In this paper, we analyzed transient changes, in the thickness distributions of a liquid-SOG (Spin-on-Glass) film on a two-dimensionally (2-D) grooved substrate during the evaporative shrinking process. The flow due to surface tension of the shrinking liquid film was calculated. Since the film is thin, a boundary layer approximation could be applied, and fourth-order differential equations of film thickness were solved using an iteration method. The viscosity and the shrinkage rate were assumed to be functions of the concentration of the solvent in the film. When the parameter of ratio [(surface tension)/{(viscosity)×(shrinking speed)}] is large and the width of the grooves is small, final surface undulations of the film are shallow. The effect of the centrifugal force was also analyzed