Carbide formation upon heat treatment of molybdenum layers deposited on carbon substrates: Comparison of experimental data with a cellular automaton model

Abstract

Manipulation of the adhesion of copper on carbon is crucial for the production of copper-carbon composites as potential high-performance heat sinks in electronic devices. A thin 100-nm sputter-deposited molybdenum (Mo) interlayer between copper and carbon increases adhesion significantly after thermal treatment. Mo layers of 100 nm have been sputter-deposited on a plane of carbon substrate. SIMS measurements have been performed after rapid heating and subsequent thermal annealing of the samples at the temperatures 400, 500 and 600°C for 1 min. While the carbon signal measured with SIMS in the Mo interlayer for the sample annealed at 400°C is very low, a higher-carbon signal at the interface has been detected after annealing at 500°C. Annealing the sample at 600°C yields a high-carbon signal throughout the whole Mo interlayer resulting from the formation of Mo2C. A cellular automaton model for parallel carbon-Mo layers has been designed in order to simulate the influence of the grain boundaries for the reaction and diffusion process. Comparing the results of the simulation and the experiment, the previously drawn assumption that grain boundary diffusion plays a crucial role for the growth kinetics of Mo2C at the Mo-C interface could be corroborated. Copyright © 2008 John Wiley & Sons, Ltd.