Growth of nanopillar CNx layer during impulse plasma deposition

Abstract

The aim of our research was to investigate the stages of the layer growth during an IPD process.The materials examined were CNx coatings produced on Si substrates by a number of plasma impulses (80–8000). All the samples were processed under the same process conditions. Gaseous nitrogen and nitrided graphite (the internal electrode of the coaxial accelerator) were used as the sources of nitrogen and carbon atoms, respectively. The layers were primarily examined by TM AFM and SEM techniques and also by TEM, XPS. The nanohardness of the deposited material was also determined.Based on the microscopic studies we found that during the deposition process, the layer morphology changed significantly with increasing number of the plasma impulses. Initially (the first growth stage-thin layers) flat, wide islands are formed as a result of the surface migration of clusters. An increase of the number of the plasma impulses leads to the formation of specific separated nanopillars. The final structure of the thick layers contains the two zones: the internal zone built of a homogeneous material and the external zone with a highly anisotropic structure.Thus far, no structure of this type was observed during the IPD processes. The mechanism of the layer growth is difficult to explain. It probably involves accumulation of heat, and thus it may be a result of layer recrystallization.