화학공학소재연구정보센터
Thin Solid Films, Vol.459, No.1-2, 276-281, 2004
Solid state de-wetting observed for vapor deposited copper films on carbon substrates
Copper-Carbon composites are a good example for novel materials consisting of components with extremely different physical and chemical properties. They have a high potential for an application as heat sinks for electronic components, but the joining of the two materials is a difficult task. To obtain reasonable mechanical and thermal contact between copper and carbon the following route was chosen. First glassy-carbon substrates were subjected to an RF-Nitrogen plasma treatment. Then 300 nm thick copper coatings were sputter-deposited on the plasma treated surface within the same vacuum chamber. Finally, the samples were removed from the deposition chamber and either investigated immediately or thermally annealed at 850 degreesC under high vacuum conditions (10(-4) Pa). While non-annealed copper-coatings were continuous and showed excellent adhesion values of approximately 700 N/cm(2), the heat treated samples lose their continuity by a de-wetting process. At the beginning holes are formed, then a labyrinth-like morphology develops and finally the coating consists of isolated droplets. All these processes occur well below the melting temperature of copper and were observed by AFM and SEM. The mechanism of this solid-state de-wetting process is investigated in relation to the recent literature on de-wetting and its consequences on the manufacturing of copper-carbon composites are discussed. (C) 2004 Elsevier B.V. All rights reserved.