A Simple Diffusion Model of Surface Modification by Plasma

Abstract

A simple two-media diffusion model of thin film deposition on material surfaces by plasma techniques has been developed. In accordance with the model the modified surface is considered to be constituted of a united compound layer, adjacent to a diffusion zone. The layer thicknesses of the zones, as functions of time, are described by a simple differential equation: dg/dt = α/g — β, where α and β are parameters of the zones. Parameter α takes into account the diffusion contribution to the layer thickness growth, parameter β the contribution of the surface erosion arising at the plasma/solid surface during the plasma treatment. Under negligible erosion effects, the model reduces to Wagner's two-phase diffusion model, and the thickness growth is described by the parabolic law. The model can be used for an experimental determination of the effective diffusion coefficients and the erosion rate during plasma treatment of material surfaces.