Study of silane films on aluminium by means of spectroscopic ellipsometry and Auger electron spectroscopy

The feasibility of using Spectroscopic Ellipsometry (SE) for the characterisation of silane films deposited on aluminium substrates is demonstrated in the case of the non-functional bis-1,2-(triethoxysilyl)ethane (BTSE) and bis-functional bis-(3-triethoxysilylpropyl)tetrasulfane (BTESPT) silanes. This method measures the polarisation change of the light due to the interaction with the sample surface. It is called spectroscopic if the measurement is performed at various wavelengths within the spectral range. In this paper, the set up of optical models used to interpret the SE data of both silane/Al systems are presented. A few examples of different applications of SE for silane characterisation are given. Direct evidence of modification in BTSE layer structure, induced by the curing of the silane coated panels is underlined using SE. The effect of Al surface pre-treatments on the thickness and morphology of BTESPT layers is presented. It is also demonstrated that Auger Electron Spectroscopy (AES) can be employed as a complementary technique permitting the validation of the optical results.