Amorphous silicon carbide nitride (SiCN) films have been deposited in a dual ion beam sputtering deposition (DIBSD) using a SiC target. Films with various compositions were obtained by changing the nitrogen and argon gas ratio in the assisted ion source. Mechanical properties of the SiCN films were evaluated by Nano-indentation in N2 ambient. Surface morphology of the films was characterized by an Atomic Force Microscope (AFM). The microstructure and chemical bonding correlating with behavior of the films were studied by a Fourier transform infrared spectroscopy (FTIR) and a laser Raman spectroscopy. The results show that N2 proportion in the assisted ion source has a great effect on the structure and properties of the films and the mechanism was discussed in brief.