Preparation of CNx-phases using plasma-assisted and hot filament chemical vapour deposition

Results are reported from a systematical investigation of deposition of binary C-N-phases in a wide substrate temperature range. The experiments are carried out in a r.f. assisted chemical vapour deposition (CVD)-apparatus. A hot filament is positioned between the electrodes to support the generation of activated species and a negative bias is applied to the substrate to increase their energy. The deposition temperature ranged from 200 degrees C without up to 1000 degrees C using hot filament. Different carbon-precursors and Ar/H-2 gas ratios were tested. The results can be summarized as follows. The films deposited at temperatures up to 250 degrees C have mostly an amorphous polymer structure. Paracyan-like coatings grow preferably in the temperature range 600-650 degrees C. At temperatures higher than 650 degrees C using a hot filament technique with r.f.-plasma and bias enhancement the deposition rare decreased strongly. However, crystalline objects could be observed on the silicon substrate. Some of the X-ray diffraction peaks of those samples coincide with reflections of covalent C3N4 phases, but reflections from alpha- or beta-Si3N4 are recorded additionally. Deposition experiments on inert substrates, for example nickel, but no CNx phases could be produced until now. (C) 1998 Elsevier Science S.A. All rights reserved.