XPS study of siloxane plasma polymer films

journal article in Web of Science

English

Plasma polymer films based on the siloxane bond are very interesting materials for their electronic, optical, thermal and mechanical properties. Especially, plasma polymers prepared from organosilicon monomers are fascinating materials due to the possibility to vary the degree of organic/inorganic character and the degree of cross-linking of the material. If such a plasma polymer is aimed to be applied for joining with another material, the physical and chemical surface properties will determine a type of interfacial bonding between the two materials in contact. Therefore, surface morphology, wettability, chemical composition and chemical structure at the film surface are of important role. Plasma polymer films were deposited from hexamethyldisiloxane, dichloro (methyl) phenylsilane, vinyltriethoxysilane, and tetravinylsilane vapor mixed with oxygen gas using an RF helical coupling deposition system. The process conditions (power, flow rate) and the sample position in plasma chamber (plasma zone, remote plasma) can vary the physical and chemical properties of deposited plasma polymers with respect to the used monomer or a mixture. The composition of elements in the surface region (top 6-8 nm) of the deposited films was studied by X-ray-induced photoelectron spectroscopy (XPS) on an ADES 400 VG Scientific photoelectron spectrometer using MgKá (1253.6 eV) or AlKá (1486.6 eV) photon beams at the normal emission angle. Functional species at the film surface are necessary for chemical bonding with thermosetting resins. The concentration of vinyl groups at the surface was therefore analyzed via Br atoms, which can react with the vinyl groups producing brominated surface. Results were compared with those of XPS curve fitting of the C 1s core level for the virgin surface. Aging effects of plasma polymer films stored at standard laboratory conditions were investigated by employing XPS. Postdeposition contamination and oxidation of films were carefully observed. An increase of oxygen atoms at the film surface with time is accompanied by changes in bulk atomic concentrations. The measurement of the concentration depth profiles was performed by sequentially applying Ar ion-beam sputtering and XPS analysis.

[C] Radio frequency (RF); [X] XPS/ESCA

BÁLKOVÁ, R.; ZEMEK, J.; ČECH, V.; VANĚK, J.; PŘIKRYL, R.

2003

1. 1. 2003

0257-8972

Surface and Coatings Technology

174-175

174-175

Swiss Confederation

1159

1163

5