Carbon nitride films were deposited on to silicon and sodium chloride substrates by ionised magnetron sputtering. The influence of an inductively coupled r.f. plasma generated between a d.c. magnetron sputtering target and the substrate, and d.c. bias voltages at the substrate, on the deposition rate, and chemical structure of the film was investigated. The films were characterised by Fourier transform infrared spectroscopy (FTIR) and Rutherford back-scattering (RBS), and the discharge was studied by optical emission spectroscopy (OES). When pure nitrogen was used for the sputtering gas with substrate bias voltages between - 100 and + 100 V, the deposition rate increased with the presence of the inductive plasma, while the chemical structures of the films were unchanged. The deposition rates of films deposited with an argon/nitrogen gas mixture increased sharply with the presence of inductive plasma when the substrate bias voltage was above the floating potential. The films deposited in an argon/nitrogen mixture with the inductive plasma with positive substrate bias showed higher contents of sp and sp(2) hybridised carbon bonded with nitrogen, than those without the inductive plasma and/or with negative bias voltages on the substrates. The results can be interpreted in terms of the selective etching of nitrogen, and sp and sp(2) hybridised carbon in the films by ions in the plasma.