Effects of varying nitride concentration in Ar:N2 sputtering of indium-tin-oxide film for use as electrode in resistance switching device

In this paper, we have observed the deposition of ITO films using different mixtures of Ar and N₂ gases, and examine the effects of increasing the N₂ concentration. Compared to the use of pure Ar to deposit pure ITO film, incorporating N₂ with Ar for the deposition causes many differences in the structural and optical characteristics of the ITON film. Material analyses, including scanning electron microscopy (SEM) and atomic force microscopy (AFM), confirm the surface morphologies of the ITON films for different ratios of Ar and N₂. Depositions using N₂ induced large surface modifications on the ITON films. In addition, the X-ray diffractometer (XRD) results suggested that increasing the concentrations of N₂ will alter the originally polycrystalline ITO film to an amorphous ITON film under conditions of higher N₂ gas flow. As for optical properties, the higher N₂ gas flow caused a decrease in the film transparency, especially for shorter wavelengths below 500 nm within the visible spectrum. As for electrical properties, ITON films all exhibit lower conductivity than the pure ITO film, possibly due to the decrease of carrier concentration and carrier mobility. We then applied these results in an HfO₂-based RRAM, where the ITO film acted as a top electrode, in order to examine the effects on the forming processes. Experimental results show that while the distributions of forming voltages exhibited very little difference, the self-compliance current varied with the concentration of N₂ gas.