Elektronenspektroskopische Charakterisierung der Adhäsion von Triazinderivaten und Cyansäureestern auf Siliziumoberflächen

Triazine derivatives are used as a model of network forming polymer adhesives that combines high thermal stability with low dielectric loss and good chemical resistance. The characterization of triazine containing molecules by electron spectroscopy improves the understanding of the adhesion properties. Due to their importance in technical applications silicon wafers have been used as substrates. Thin films of 2,4,6-tris-(2,2-bisphenyl-propane)-1,3,5-triazine, formed on silicon wafers by vapor deposition, were studied by X-ray Photoelectron Spectroscopy (XPS), Ultraviolet Photoelectron Spectroscopy (UPS) and Metastable Impact Electron Spectroscopy (MIES). Three different surfaces (clean Si(100), native silicon oxide and Si(100) with a saturation coverage of H20) were used as substrates. Angle dependent XPS as well as MIES reveals a preferential orientation of the molecules in the first adlayer on the surfaces, which leads to an adsorption model. The adsorption of the first layer on all three silicon substrates is governed by the interaction of the trioxytriazine rings with the substrate surfaces. This adsorption model is supported by a force field calculation of the p-CPC trimer molecules. In addition, the combination of electron spectroscopy and AFM reveals a layer-by-layer growth mode of the p-CPC molecules up to 10 nm film thickness.