Tin nitride thin films fabricated by reactive radio frequency magnetron sputtering at various nitrogen gas ratios

• Control oxidation state of Sn and SnN.
• Surface energy changed with N2 ratios.
• The dominant phase of SnN was controlled by change of N2 gas ratio.

Sn nitride thin films are remarkable materials that can be implemented in applications such as microelectronic devices and recording media. This paper presents the analysis of the various Sn nitride thin films' structural, electrical, and chemical properties using a surface profiler, X-ray diffraction, a 4-point probe, X-ray photoelectron spectroscopy (XPS), and distilled water and ethylene glycol contact angle measurements. The Sn nitride thin films were prepared via radio frequency magnetron sputtering. The thickness of Sn nitride thin films decreased in the regions where N2 gas ratios ranged from 20% to 100%. The surface resistance decreased from 6.34 × 104 to 56.2 Ω/sq with gradual increasing of N2 gas ratios from 20% to 100%. Change in crystallinity of the films was observed as N2 gas was progressively introduced, from metallic Sn to the amorphous Sn nitride phase. The high resolution XPS spectra indicates that the intensity of Sn2 + increased, while those of Sn4 + and Sn0 decreased with increasing N2 gas ratios, confirming the bond formation of Sn and N. The total surface free energy (SFE) varied by changing the N2 gas ratio. When the N2 gas ratio in the sputter gas was low (less than 20%), the dominant contributing factor to the total SFE switched from polar to dispersive SFE. In samples where the N2 gas ratio was over 20%, the major contribution to the total SFE was dispersive SFE.