Determination of resputtering yields in carbon nitride films grown by dual ion beam sputtering

Resputtering phenomena play an important role in the growth of carbon nitride films assisted with low energy N+2 ions. CNx films [x ranging between 0 and 0.6, as determined by Auger electron spectroscopy (AES)] have been prepared by dual ion beam sputtering and characterized by several techniques [AES, Rutherford backscattering (RBS), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), transmission electron diffraction (TED)]. In this work we have estimated the resputtering yields of carbon and nitrogen atoms in terms of the deposition rate and the surface composition, as determined by AES depth profiling and RBS measurements. Carbon resputtering yield in the order of 0.3 carbon atoms per incident N+2 ions and nitrogen re-emissions higher than 90% are obtained. A threshold is found for the arrival rate ratio (ARR) of N+2 ions to C atoms of about 3.0. Higher values of ARR will inhibit the growth of the film. The influence of the energy of assistance and the electric properties of the substrates in the resputtering process are also discussed.