Spin coating is a transient process of flow and mass transfer. Coating thickness and uniformity depend on the competition between centrifugally driven drainage of the liquid film and concentration-driven evaporation of solvents. Volatile solvents are transported in the film by convection and diffusion, and on reaching the free surface can vaporize and depart by diffusion and convection in flowing gas. Falling diffusivity, rising viscosity, and changing rheology as solvents evaporate from the remaining film complicate the process. An accurate theory of spin coating would permit better design and control of the process in its various applications. Basic principles of the flow mechanics, solvent transport, and film formation are laid out and stages of spin coating are identified.
|Original language||English (US)|
|Number of pages||9|
|Journal||Journal of Imaging Technology|
|State||Published - Aug 1 1987|