Growth and characterization of hard and elastic carbon nitride thin films

Hard CNx films were prepared by nitrogen ion beam assisted deposition (IBAD) of evaporated carbon on silicon wafers with a nitrogen ion energy of 100 to 1200eV, ion/neutral transport ratios from 0.7 to 1.7, and deposition temperatures from RT to 1000°C. The films were characterised by ERDA, XPS, TEM, ED, EELS, and nanoindentation.
By varying the deposition parameters a maximum nitrogen content of < 33 at.% was found at N/C transport ratios of about 1.2. Further increase of this ratio did not result in a higher nitrogen content in the films. XPS measurement reflects a shift of the main chemical state of the nitrogen bonds with changing nitrogen content of the films and with increasing deposition temperature. The nitrogen content of the films was drastic decreased with increasing temperatures > 600°C.
EELS investigations have shown weak changes of the plasmon peak position and the sp2/sp3 ratio with increasing deposition temperature in correlation to the nitrogen content of the carbon films.
Nanoindentation techniques have been used to investigate the mechanical properties such as hardness and elastic modulus of the films. High hardness and elastic modulus values for those composites have been found. All measured structural and mechanical properties correlate with the analysed nitrogen content.