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C. Eisenmenger-Sittner, B. Schwarz, E. Neubauer, E. Eiper, J. Keckes:
"ADHESION IMPROVEMENT OF COPPER (Cu) ON CARBON (C) BY PLASMA TREATMENT AND MOLYBDENUM (Mo) INTERLAYERS";
Poster: International Conference Metallurgical Coatings and Thin Films 2006 - ICMCTF'06, San Diego / Californien; 01.05.2006 - 05.05.2006.

ADHESION IMPROVEMENT OF COPPER (Cu) ON CARBON (C) BY PLASMA TREATMENT AND MOLYBDENUM (Mo) INTERLAYERS

C. Eisenmenger-Sittner, B. Schwarz, E. Neubauer*, E. Eiper**, J. Keckes***
Institute of Solid State Physics, Vienna University of Technology, Vienna, Austria
*ARC Seibersdorf Research, Dept. Materials Research, A-2444 Seibersdorf
**Erich Schmid Institute, Leoben, Austria
***Materials Center Leoben/ Erich Schmid Institute, Leoben, Austria

The thermomechanical properties of C-fiber reinforced Cu-C Metal Matrix Composites which are potential materials for high performance heat sinks depend crucially on wetting and adhesion between the chemically immiscible elements Cu and C.
This work presents two approaches to adhesion manipulation: (i) the activation of the C-surface by a treatment in Nitrogen (N2) Radio Frequency (RF) plasma and (ii) the deposition of a Mo-interlayer on the C-surface.
Both approaches significantly increase the adhesion of 4 µm thick Cu-coatings deposited by magnetron sputtering immediately after pre treatment. Heat treatment (30 min, 800°C, High Vacuum furnace) leads to a drastic loss in adhesion for the plasma treated samples while the samples containing the Mo-interlayer retain excellent adhesion values.
Thermal cycling experiments (RT - 500°C) with X-Ray Diffraction (XRD) measurements of the tensions in the Cu-coating show comparable results: The Cu-coating on the plasma treated sample delaminates after one cycle. The sample with the Mo-interlayer can go through several cycles and is able to sustain thermally induced tensions.
The difference in the response of the two sample types to post deposition thermal treatment can be tracked back to the de-wetting behavior of Cu on the different substrates. Void formation is observed at the Cu-C interface in the case of plasma treatment but not for samples with a Mo-interlayer.
This work is supported by the Austrian Science Fund (FWF) under grant Nr. P-14534.