Authors: Franke, E.K.; Birnie, D.P. III
Source: Journal of Materials Science Letters 14 (1995) 1807-1809

Abstract: Spin coating is in general a convenient method and reproducible method for applying highly uniform thin films to substrates of all kinds. It starts by dispensing the precursor solution onto the chosen wafer, the rotation is initiated, causing most of the solution to be rapidly flung from the substrate by inertia. During fluid flow and thinning stages, there will be strong inertial forces that create both shear and elongational fields in the fluid. This paper investigates whether these shear and stretching gradients can be effective at causing preferential fiber orientation when spin coating of composite solutions is performed. It is shown that fibers in a composite solution orientate themselves with a general radial orientation during spin coating. The largest fraction of fibers align themselves to within 15^o of their ideal radial orientation.