S. Nowak

Electron cyclotron resonance plasma experiment for in situ surface modification, deposition, and analysis

An electron cyclotron resonance plasma source which allows in situ surface modification and thin film deposition combined with surface analysis by x‐ray photoelectron spectroscopy (XPS) is presented. This experiment enables well defined surface modification studies to be performed. We discuss the experimental details of this plasma source as well as the main discharge characteristics as a function of gas, pressure, and geometry. Using plasma diagnostics, a Langmuir probe and an ion energy analyzer, the ion density, the electron temperature, and the ion flux were determined. Two examples of applications analyzed by XPS, one for surface modification and one for thin film deposition, confirm the ability to produce well defined and contamination‐free surfaces.

Surface modifications of polypropylene after in-situ Ar and N2 plasma treatments: an XPS study

Abstract Argon and nitrogen plasma treatments of isotactic polypropylene were performed in an electron cyclotron resonance (ECR) plasma. The effect of treatment time, pressure and RF bias on the surface was investigated by X-ray photoelectron spectroscopy and a comparison is made with low-energy Ar-ion bombardment. The plasma treatment is found to produce similar but less pronounced effects than the ion bombardment. The effect consists of a change of the physical and morphological properties as detected by the variations in the valence band and the C1s position, width and shape. The nitrogen incorporation shows significant differences depending on the three investigated parameters. The ion energy appears to be a determinant parameter.

Plasma treatment of polymers: the effect of the plasma parameters on the chemical, physical, and morphological states of the polymer surface and on the metal-polymer interface

The results of the characterization of plasma-treated polypropylene (PP) and polymethylmethacrylate (PMMA) by X-ray photoelectron spectroscopic, atomic force microscopic (AFM), and surface resistivity measurements are presented. Chemical, physical, and morphological modifications of the polymer surface were investigated. The importance of the neutral gas of the electron cyclotron resonance-radio frequency (ECR-RF) plasma treatment is principally demonstrated. Large differences between the effects of noble and reactive gas plasmas were observed by AFM and surface resistivity measurements. However, the maximum sticking coefficient of evaporated Mg on PP is similar for both Ar and N2 plasma treatments.

X‐ray photoelectron spectroscopy study of the polypropylene–magnesium interface after in situ plasma and ion treatment: Sticking, bonding, and film growth

A study on a model system for polymer–metal interface formation after surface treatment is presented. We discuss a comparative x‐ray photoelectron spectroscopy analysis of in situ plasma and ion‐treated polypropylene surfaces with an evaporated magnesium overlayer. The different surface treatments are found to enhance the sticking probability of the metal vapor on the polymer surface considerably. Depending on the kind of surface treatment, different types of bonding of the Mg with the polymer are observed. The analysis of the excited plasmons is used to gain information about the interface formation. The experimental results suggest an island growth mode of the Mg.

Initial stages of titanium carbide growth by plasma-sputter deposition on stainless steel

Abstract The chemistry in the initial stage of growth of plasma-sputter deposited titanium carbide (TiC) on stainless steel has been investigated as a function of substrate and plasma conditions using X-ray photoelectron spectroscopy (XPS). In the first stage of the deposition process the plasma-steel interaction results in the formation of free-carbon-like amorphous carbon and polymer-like carbon. We found that the addition of nitrogen (partial pressure two times higher than CH 4 ) in the initial stages of growth prevents the deposition of free carbon at the interface by the formation of a nitride interface containing nitrides on the substrate surface and titanium nitride (TiN). The synthesis of volatile hydrogen cyanide (HCN) on the substrate surface prevents the formation of free carbon. Our observation suggests that the addition of nitrogen during the initial stages of deposition improves the adhesion as well as the reproducibility of the adhesion of TiC on stainless steels deposited by reactive sputtering techniques.

Enhancement of the sticking coefficient of Mg on polypropylene by in situ ECR-RF Ar and N2 plasma treatments

A study of the sticking coefficient of Mg vapour on in situ Ar and N2 plasma-treated polypropylene (PP) is presented. After exposure of the pretreated sample to a determined amount of Mg vapour, X-ray photoelectron spectroscopy (XPS) allows measurement of the adhered Mg amount at the polymer surface and the chemical nature of the interface. The sticking coefficient on an as-received sample is zero and is increased to several tenths depending on the pretreatment conditions, namely the nature and the pressure of the neutral gas, the treatment time, and the applied RF-bias. Relations between the plasma parameters, the XPS measured surface state before the metallization, and the sticking coefficient are investigated.

X‐ray photoelectron spectroscopy study of growth of thin cerium films on polypropylene

From x‐ray photoelectron spectroscopy (XPS) measurements of thermally evaporated cerium films on polypropylene (PP) we conclude that an ion bombardment pretreatment of the substrate significantly improves the deposited amount of cerium. The metal–polymer interface state is dependent upon the ion bombardment of the PP substrate. For a mild bombardment (Ar+ ions of kinetic energy less than 500 eV and doses less than 1015 ions/cm2) we observed the formation of Ce–C bonds, which are not observed if we apply a more energetic ion bombardment (ions kinetic energy 3 keV, doses≳1016 ions/cm2). The effect of the ion bombardment on the cerium film formation can be summarized in an increased coverage of the polymeric substrate for the same thickness of the cerium film. We find that the cerium film grows with a Volmer–Weber mechanism and the difference between treated and untreated samples consists in an increased coverage of the substrate by cerium for the treated samples. A new kind of plot of the XPS data is used t...

XPS-Study of Metal-Polymer Interfaces After Polymer Surface Treatment by Ion and Plasma Techniques

A study of the effects of surface treatment of polypropylene on the deposition of thin metal films is presented. The polypropylene samples were treated in a low-pressure air plasma in one case and sputtered by argon ions in the other case. XPS was used to detect compositional surface modifications. Plasma treatment leads to surface oxidation, whereas the sputtering results in oxygen-free surfaces for in-situ analysis. After surface treatment, thin films of Mg, Ca and Ce were deposited. Depending on the surface treatment, we find indications for different bonding mechanisms and very different sticking probabilities. For the case of oxidized surfaces, the formation of a metal-oxygen-polymer complex is anticipated, whereas for oxygen-free surfaces a metal-carbon bond is likely to be formed.