Synthesis of carbon nitride films by ECR sputtering deposition method

Carbon nitride (CN_x) films were prepared by Electron Cyclotron Resonance (ECR) sputter deposition using a carbon target and nitrogen ambient. The deposited films were evaluated with XPS, IR, Raman spectroscopy, SEM, and AFM. The nitrogen concentration, chemical bonding, and surface morphology of the deposited films were dependent on substrate self-bias potential, corresponding to ion irradiation energy. As substrate self-bias potential decreased, nitrogen-carbon atomic ratio (N/C) increased until -50 V and then decreased below -60 V. The maximum of N/C ratio reached 1.38, which was for almost stoichiometric C₃ N₄. Crystalline carbon nitride films were formed for substrate temperature above 600°C. The X-ray diffraction pattern of the deposited crystalline film was similar to that of the predicted α and β-C₃N₄. These experimental results suggest that the changes of structure and chemical bonding state occur at a substrate bias potential of around -50 V and that the condition seems to be favorable for carbon nitride formation