Asymptotic Analysis of Thin-Film Formation during Spin Coating

Abstract

In this paper the issue is addressed of how a liquid film of non-uniform thickness thins to a planar profile during spin coating. Asymptotic method is applied to a case in which the initial film thickness is even in radial coordinate and the peripheral effects of liquid film are assumed to be negligible. The analytical expressions for the transient film profile near the rotating axis are obtained. The analysis reveals the effects of gravitational and surface tension forces as well as the effect of inertial force on film formation in the initial and the late stage of process.