Analysis of Thin Films with Slightly Rough Boundaries

Abstract

Technological procedures often produce thin films with rough boundaries as for example, semiconductor films prepared by various chemical methods. If roughness of the boundaries of the films is very small, i.e. if the rms values of the heights of boundary irregularities are equal to several nanometers, it is very difficult to carry out a detailed analysis of the films. Spectroscopic ellipsometry and atomic force microscopy represent two experimental techniques enabling us to determine some important parameters of these films (e.g. thickness) together with the main statistical quantities characterizing slight (nanometric) roughness of their boundaries.

In this paper a method will be presented based on a combination of variable angle spectroscopic ellipsometry, spectroscopic reflectometry and atomic force microscopy enabling us to determine the optical parameters and the most significant statistical parameters of the rough boundaries characterizing the slightly rough single layers.

Within the method the generalized Rayleigh-Rice theory published elsewhere will be used for interpreting experimental data obtained from both the optical techniques, i.e. variable angle spectroscopic ellipsometry and spectroscopic reflectometry.

The method will be illustrated by presenting experimental results achieved by applying the method to slightly rough surfaces of single crystals of GaAs covered by very thin surface layers (i.e. by native oxide layers).

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