Pierre Vanden Brande

Nucleation and initial growth of copper electrodeposits under galvanostatic conditions

Abstract First stages of copper electrodeposition on amorphous carbon and polycrystalline silver substrates are studied under galvanostatic conditions. An island growth mode is observed on the two types of substrates but for equivalent conditions the cluster density is higher on silver substrates than on carbon substrates. Dissolution of some copper clusters occurs a short time after the onset of electrolysis. This can be explained by local changes in supersaturation due to current microdistribution at the cathode surface.

Determination of the chemical and physical properties of hydrogenated carbon deposits produced by d.c. magnetron reactive sputtering

Abstract Hydrogenated carbon deposits on silicon substrate have been prepared by magnetron-enhanced reactive sputtering in a C 2 H 2 -Ar gas mixture with a carbon autofeeding target system. The hydrogen content and the density of the hydrogenated carbon deposits have been determined by elastic recoil detection analysis and related to the C 2 H 2 : Ar gas flow ratio. The characteristics of carbon-hydrogen and carbon-carbon bonds have been investigated by Fourier transform IR spectrometry. The mechanical properties were investigated by nanoindentation. This systematic study reveals a dependence of film properties on gas composition. This dependence can be used to tune film properties to specific applications. As the acetylene flow increases, the hydrogen concentration increases, and films have a decreasing density, decreasing hardness and decreasing Youngs modulus.

Study of the formation of a carbon layer on a sputtering target during magnetron-enhanced reactive sputtering

Abstract The goal of this work is to estimate and to discuss the optimum conditions for the realization of hydrogenated carbon deposits obtained by magnetron-enhanced reactive sputtering in a C 2 H 2 -Ar gas mixture with a carbon autofeeding target system. Hydrogenated carbon layers can be obtained by reactive sputtering of a copper target poisoned by carbon compounds during the deposition process. It is shown that the target poisoning rate, composition and structure depend on the gas composition (C 2 H 2 -Ar) and on the sputtering conditions (target current). The target poisoning rate is compared with the deposition rate of the hydrogenated carbon deposit on a silicon substrate and related to an analysis of the gas discharge by emission spectroscopy for different experimental conditions. The structure of the carbon-poisoning layer is also compared with the structure of the carbon layer deposited on a substrate. The hydrogen-to-carbon ratio is determined on both the target and the substrate by elastic recoil detection analysis.

Influence of the plasma pretreatment of a steel substrate on the development of an hydrogenated carbon deposit

The first stages of the growth of a hydrogenated carbon deposit have been investigated by Auger electron spectroscopy on plasma-etched steel substrates. The deposit-to-substrate Auger peak-to-peak intensity curves vs. the quantity of deposited matter are characteristics of the growth mode which is itself very dependent on the plasma cleaning procedure. Substrate cleaning promotes a layer-by-layer growth mode whereas its absence induces an island growth mode. The steel substrate decontamination not only increases the adhesion between the carbonaceous film and the steel surface but also improves the protective properties of the coating. Finally it is shown that on a decontaminated steel sheet, a film of 1.2 nm can be a perfect covering.

Nucleation and initial growth of copper deposits by high rate magnetron-enhanced sputtering

Abstract Practically it is very important to know whether a very thin film is completely covering or not, for instance in the realization of very thin barrier layers. For this reason we propose a method to investigate by Auger electron spectroscopy the first stages of copper growth on amorphous carbon and polycrystalline silver substrates. The copper deposits are produced by high rate magnetron-enhanced sputtering. It is shown that the growth mode is a function of the substrate surface nature, linked to the ratio of adsorption energy to cohesion energy. When an island growth mode is observed the mean cluster size and the mean cluster density are calculated from the Auger results.

Characterization of the first stages of the formation of metallic sputtered deposits and electrodeposits by Auger electron spectroscopy

The first stages of copper growth on amorphous carbon and polycrystalline silver substrates by high rate magnetron-enhanced sputtering and the first stages of nickel electrodeposition on polycrystalline silver substrates have been investigated by Auger electron spectroscopy because direct observation by scanning electron microscopy or transmission electron microscopy was not possible. The deposit-to-substrate Auger peak-to-peak intensity ratio curvesvs. the quantity of deposited matter have been shown to be characteristic of the growth mode. The method allowed us to distinguish between the island growth mode, the layer-by-layer growth mode, and the coalescence stage. When an island growth mode was observed (on carbon substrates in copper sputtering and on silver substrates in nickel electrodeposition) the approximate mean cluster size and mean cluster surface density have been calculated from the Auger results.