J. Erichsen

Mechanisms of argon ion-beam surface modification of polystyrene

Abstract The surface characteristics of polymers are important factors determining their interfacial properties and their technological performance. Changes in physical and chemical properties of a polymer film may be induced by subjecting the material to a variety of surface modification techniques, one of which is ion-beam modification. In order to understand the underlying mechanisms X-ray photoelectron spectroscopy (XPS) was used to study the alterations of the polystyrene (PS) surface after Ar-ion treatment under well controlled conditions with low ion doses from 10 12 to 10 16 cm −2 . The ion bombardment leads to surface functionalization, loss of aromaticity, and free radical formation. Induced surface cross-linking and the formation of polar groups raised the surface glass transition temperature of PS film.

Etching rate and structural modification of polymer films during low energy ion irradiation

Various polymers were sputtered with low energy Ar+ ions of 1 keV in order to determine their etching rate. Hydrocarbons, oxygenated, fluorinated and nitrogen-containing glassy polymers with a broad range of the glass transition temperature (Tg) were chosen. The etching rate was measured using a profilometer, and X-ray photoelectron spectroscopy. At the same time the surface chemical modification, and the surface glass transition temperature were studied. Comparing the sputter rate to the various polymer properties a correlation among the Tg, cross-link density, and sputter rate was found. In addition, the sputter rate as a function of the integral ion fluence proved to exhibit a sharp increase in the initial regime of very low fluence. The results are discussed in terms of the characteristics of the polymers

Fundamental Aspects Of Polymer Metallization

Metallized plastics are used extensively in applications ranging from food packing to microelectronics1,2. Particularly the latter field has stimulated intensive research throughout the last decades1–6. In view of the great need for further miniaturization and reduction of propagation delay in future device generations aluminum will increasingly be replaced by the lower resistivity copper, and polymers are seen as potential low-permittivity (low-k) dielectrics even for on-chip interconnect5,6. First chips involving Cu and the polymer SiLK® (DuPont7) have already been fabricated by IBM8.

Molecular Weight Dependence of the Surface Glass Transition of Polystyrene Films Investigated by the Embedding of Gold Nanoclusters

We probed the glass transition temperature T g at the surface of polystyrene (PS) samples with different molecular weights by embedding of gold nanoclusters. The embedding of the nano-clusters was monitored by x-ray photoelectron spectroscopy (XPS). The onset embedding temperature determined by XPS was taken as a measure for the T g at the surface. We observed a small decrease of T g at the surface relative to the bulk for all molecular weights (Δ T g = 2.5- 8.5 K). This decrease is small for short chains (M W = 3.6 kg/mol) and grows to a saturation for M W ≥ 44 kg/mol (Δ T g ≍ 8 K). This is in accord with the smaller relative increase in the number of degrees of freedom between bulk and surface for shorter chains.

Silver diffusion in Fe40Ni38Mo4B18 metallic glass under high vacuum

Abstract In order to ascertain reports on unexpected dispersion of noble metals in Fe 40 Ni 38 Mo 4 B 18 glass the diffusion behaviour of 110m Ag was studied by the radio-tracer technique. Silver did not show a clear penetration profile in high vacuum, confirming the crucial role of the annealing atmosphere.

Adsorption of Noble Metal Atoms on Polymers

Metallized polymers are nowadays of considerable technological importance and are widely used in industry ranging from food packing to optical data storage. A detailed understanding of the metal/polymer interface properties plays a key role in most applications of metallized polymers. During the last few years, much work has been performed to study the different aspects of metal/polymer interface formation using various microscopic and surface-sensitive techniques. For recent and detailed reviews on metal/polymer interfaces, we refer the reader to refs. 1 and 2 and the article by F. Faupel et al. in the present proceedings. In this article we only consider the metal adsorption phenomena during metal/polymer interface formation by thermal evaporation of a noble metal onto a polymer.

Comparative analysis of the nucleation and growth of copper on different low-k polymers

In this work we present investigations of the nucleation and growth of evaporated copper on several low-k polymers. The evolving interfaces were characterized using transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results were compared between the PMDA/ODA polyimide, Teflon AF 1601 and Silk ® . A diffusion coefficient for copper atoms in Silk ® determined by low energy ion-beam depth profiling in conjunction with XPS is reported.