Gas Pressure Dependence on Structural and Electrical Properties of Ni Thin Films on an Acrylonitrile-Butadiene-Styrene Resin Prepared Using Unbalanced Magnetron Sputtering Assisted by Inductively Coupled Plasma

Abstract

We fabricated Ni thin films on an acrylonitrile-butadiene-styrene resin (ABS) substrate using unbalanced magnetron sputtering assisted by inductively coupled plasma. In order to obtain the knowledge on the effect of ion irradiation, we investigated the gas pressure dependence on the structural and electrical properties of fabricated Ni thin films. We used a Ni target (purity of 99.95%, thickness of 5 mm and diameter of 200 mm) and used Ar gas with purity of 99.9999% as the sputtering gas. The flow rate of the Ar gas was maintained at 1 sccm. As the deposition condition, we varied the Ar gas pressure within the range of 0.3-0.8 Pa. The target DC power was constant at 400 W, radio frequency (RF) power for plasma generation was 30 W constant, thickness of the Ni thin films was constant at 200 nm. Vertical magnetic flux density to the substrate was constant at 5 mT. We measured the Ar ion emission intensity corresponding to the amount of Ar ions using emission spectroscopy of Ar plasma. The surface morphology was observed by atomic force microscopy (AFM), and the crystal structure was analyzed by X-ray diffraction (XRD). The resistivity was measured using the four point probe method. We confirmed that gas pressure affected the effect of ion irradiation. The effect of ion irradiation decreased with the increase in the gas pressure and was maximum at a gas pressure of 0.4 Pa. This suggests that controlling gas pressure is very effective for controlling the effect of ion irradiation. From the AFM images analysis, the average surface grain size of the fabricated Ni thin films surfaces decreased due to the increase in the gas pressure. From the XRD spectrum analysis, the crystallite size of the fabricated Ni thin films decreased due to the increase in gas pressure. The resistivity of the fabricated Ni thin films increased with the increase in gas pressure. The minimum resistivity of the Ni thin film was 12.1×10^-6 Ωcm at 0.4 Pa. We found that the properties of Ni thin film on an ABS resin substrate can be controlled by the effect of ion irradiation.