A dual ion beam deposition apparatus was newly developed, which consists of a positive ion beam line, a negative ion beam line and an ultra-high vacuum deposition chamber. The machine can generate mass-analyzed very low energy ion beams with positive and negative charges at the same time with the ion energy range from 10 eV to 20 keV. It is possible to deposit both ions not only simultaneously but also alternatively. The machine has a wide possibility to fabricate ultra-pure materials or non-traditional materials, and is also useful to study fundamental processes of ion beam deposition and/or ion solid surface interactions. Using this new equipment, carbon nitride films were fabricated by simultaneous deposition of C^- and N⁺ ions with the ion energy varying from 50 to 400 eV. The films were analyzed by Rutherford backscattering (RBS), Fourier Transform Infrared Spectroscopy (FTIR) and Raman scattering. It was found that the maximum composition ratio (N/C)_c was about 0.9, the film structure was like amorphous carbon and the amount of C-N triple bonds tended to decrease with decreasing nitrogen ion energy.