Investigation of SiO2 layers by glow discharge optical emission spectroscopy including layer thickness determination by an optical interference effect

Abstract

When analysing transparent layers on reflecting substrates, the effect of interference causes intensity oscillations of certain spectral lines in glow discharge optical emission spectroscopy (GD-OES). As well as the chemical information that can be obtained from GD-OES depth profiles, this effect provides additional information for the determination either of layer thickness or of refractive index. Chemical characterisation and layer thickness determination were carried out on SiO2 layers deposited by different methods using GD-OES. In some cases the calculated layer thickness was compared with data gained by ellipsometry. The results of layer thickness determination using the emission lines of Si at 288 nm and Ar at 416 nm, obtained at a homogeneous thermally oxidised silicon wafer, show the present state of the art of accuracy and precision of this analytical method.