Growth characteristics of tungsten-carbon films deposited by magnetron sputtering

Tungsten and tungsten-carbon films have been deposited by direct and reactive magnetron sputtering in pure Ar and Ar-CH4 mixtures, respectively. The structural properties of W and W-C/substrate samples were investigated by cross-sectional transmission electron microscopy, concentrating on the structure of the interface regions. Both pure tungsten and tungsten-carbon films exhibit a regular columnar structure, but in the case of carbon-doped films, growth begins by the formation of a nanocrystalline alpha-W structure. At a certain film thickness, depending on the amount of the incorporated carbon, the growth of the films changes to the formation of a polycrystalline columnar structure. The carbon content is higher in the nanocrystalline part of the film, which is always present independently of the applied substrate material. (C) 1998 Published by Elsevier Science S.A.