Growth and characterisation 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 100–1200 eV, ion/neutral transport ratios from 0.7 to 1.7, and deposition temperatures from RT to 1000°C. By varying the deposition parameters a maximum nitrogen content of below 33 at.% was found at N/C transport ratios of approximately 1.2. XPS measurements reflect 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 decreases significantly with increasing temperatures above 600°C. EELS investigations show 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 of the films. All measured structural and mechanical properties correlate with the analysed nitrogen content.