Homogenous Si–C–N films of 120 nm thickness have been successfully fabricated by means of rf magnetron sputtering combined with ion implantation. These means are capable of producing various tailored stoichiometries of so far unequaled nitrogen concentration and high purity (O≪0.2 at. %, H≪0.5 at. %). The achieved compounds Si2CN4,SiCN2, and SiC2N2.2 consist of SiN4 tetrahedron layers interconnected by carbodiimid bridges. Stoichiometry, chemical binding states, and homogeneity of these layers as well as the reproducibility have been investigated by means of x-ray photoelectron spectroscopy, Fourier transform infrared, non-Rutherford back scattering spectroscopy, and resonant nuclear reaction analyses. Furthermore, sputter induced effects on the Si–C–N system during surface analytical characterization using Ar+ ions at 250 and 3250 eV for sputter cleaning have been studied carefully.