Effect of the N₂/(Ar+N₂) flow ratio on the synthesis of zirconium nitride thin films by DC reactive sputtering

We investigate the effect of the N₂/(Ar+N₂) flow ratio (F(N₂)) on the structural and the electrical properties of ZrN_x thin films deposited on Si(111) substrates by DC reactive sputtering at room temperature (R.T.), by using glancing-angle X-ray diffraction (GA-XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The films show stoichiometric ZrN structures for F(N₂) from 4.3% to 10% and changed into non-stoichiometric Zr₃N₄ structures with increasing F(N₂) from 11.8% to 25%. On the other hand, the electrical resistivity rapidly increase from 40.8 μ·cm to 1291.87 μ·cm with increasing F(N₂), which may be related to compositional changes from ZrN to Zr₃N₄. We also observed that the stoichiometric ZrN film had larger and denser granular-type grains because of it had a higher growth rate of grains than the non-stoichiometric Zr₃N₄ film.