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E. Neubauer, G. Korb, C. Eisenmenger-Sittner, H. Bangert:
"AFM AND AUGER INVESTIGATIONS OF AS-DEPOSITED AND HEAT TREATED COPPER COATINGS ON GLASSY CARBON SURFACES WITH DIFFERENT INTERMEDIATE LAYERS ";
Poster: 9th Joint Vacuum Conference, Schloss Seggau, Österreich; 16.06.2002 - 20.06.2002.

AFM AND AUGER INVESTIGATIONS OF AS-DEPOSITED AND HEAT TREATED COPPER COATINGS ON GLASSY CARBON SURFACES WITH DIFFERENT INTERMEDIATE LAYERS

E.Neubauer*/**, G.Korb*, Ch. Eisenmenger Sittner**, H.Bangert**,
* ARC Seibersdorf Research GmbH, Dept. Materials and Production Engineering
**Vienna University of Technology, Institute of Solid State Physics-Thin Film Group

As known from various references wetting of carbon by copper is very poor. Especially this fact results in a poor mechanical and thermal interface in composite materials, where a copper matrix is reinforced with carbon fibers. An advanced method for the preparation of such composites is the coating of fibers with matrix material followed by a consolidation process. For the deposition of the copper matrix in general electrochemical coating methods are used. Nevertheless vacuum technologies would have advantages because of the possibility to tailor the interface between coating and matrix.

A first approach to solve this problem is based on experiments performed on plane carbon substrates. The described experiments will investigate the influence of different deposition techniques (Electrochemical and PVD) on surface topography for copper coatings as-deposited and after a heat treatment at 800°C for 1 hour. Different growth modes were observed, depending on the cleaning procedure of the carbon surface. The characterisation of surface topography as well as the determination of coating roughness or size of grains was done by an AFM.

In order to improve the interface between copper and the substrate, different intermediate layers (Cr, Ti) were deposited onto the carbon surfaces. The AFM was used to determine the roughness of different intermediate layers with different thicknesses before and after a heat treatment. From these coating tests it turned out that no well adhering Cr layer with a thickness greater than 25nm (Ti-layer greater 200nm) could be deposited: due to the intrinsic stresses thick layers did not adhere on the substrate when deposited at room temperature.
Using the results of these investigations, a series of copper coatings on intermediate layers with different thickness was prepared by sputter deposition. Surface topography of as-deposited and samples after heat treatment were investigated and compared in terms of growth mode, grain size and roughness. Using Auger analysis the element distribution on the surface of as-deposited and heat treated samples was investigated. The conclusion of these investigations is, that atoms from the intermediate layer (Cr or Ti) are diffusing during the heat treatment from the interfacial area to the surface where they are oxidised.