Cross-sectional scanning force microscopy analysis of arc-discharge-deposited diamond-like carbon films

The surface topography and defect structure have a fundamental effect on the tribological and corrosion properties of diamond-like carbon (DLC) films. In the are discharge deposition of thin films the problem of particle ejection is always encountered. When diamond-like carbon films are deposited using a graphite cathode macroscopic particles and clusters are ejected along the carbon plasma plume. These particles can be filtered, e.g. by using a curved magnetic field, and the number of particles hitting the growing surface can successfully be reduced. However, due to elastic collisions to the chamber wall and other surfaces it is not possible to achieve complete filtering without also drastically reducing the deposition rate. In our previous work we studied the topography of the film using scanning force microscopy (SFM). In order to understand the observed topographical features better we used in this work cross-sectional scanning force microscopy (X-SFM) and cross-sectional transmission electron microscopy (X-TEM) to investigate the microstructure of the DLC films. In the cross-sectional micrographs nodular growth defects bisecting the film were observed. These nodular growth defects affect the surface topography of the film and thus affect the coating performance in tribological and corrosion applications. The connection between the carbon particles and the observed nodular defects is still under investigation.