Composition and energetic conditions of the ion flux of a direct current, N2/Ar, unbalanced magnetron sputtering plasma in front of ionized film-forming species were investigated. Plasma probe measurements and energy selective mass spectrometry were used. The results show that the total number of C-containing ions strongly depends on the N2 fraction in the discharge. It was also found that C and N atoms and ions are important during growth of fullerene-like (FL) carbon nitride (CNx) thin films.