Yeonwon Kim

To investigate the improvements in the resistance of Cu–Ni alloys to surface pitting corrosion, Cu–Ni thin films containing Al were fabricated via DC magnetron sputtering. The morphologies of the fabricated samples were obtained using a scanning electron microscopy, which yielded information on the crystal size and sample surface before and after corrosion tests. X-ray diffraction was employed for the structural characterization of the as-deposited films, and vibrational spectroscopy was used to verify the corrosion products. The corrosion behaviors of the Cu–Ni and Cu–Ni–Al samples were examined using electrochemical polarization and cyclic corrosion tests. The Al co-deposited samples showed a refined crystal size as compared to the Cu–Ni sample, suggesting that they are more susceptible to the formation of a passivation film. The corrosion current density of the Cu–Ni–Al was reduced, and the corrosion potential was lower than that without Al content. The negative shift in the corrosion potential of the Al-containing samples indicates that the Al₂O₃ film suppressed the cathodic reaction, resulting in a decrease in the corrosion rate. These results are consistent with the cyclic corrosion test results, in which no pitting corrosion is observed in the Cu–Ni–Al sample.

Time-dependent behavior of particles measured using the laser light scattering method in a remote silane plasma has been investigated using both optical emission spectroscopy and quartz crystal microbalance. Laser-scattered particles were observed from 0.3 s after the plasma ignition and scattering increased rapidly until 3.0 s. In the 0–0.3 s region where no particles were observed, SiH and Hβ emission intensity as well as Si/SiH and Hβ/SiH intensity ratios increased rapidly. Laser-scattered particles decreased in number, 3.0 s after plasma discharge, but the deposition rate measured using the quartz crystal microbalance increased linearly. The relationships between time-resolved images of particle movements and their contribution to film deposition as well as plasma characteristics such as SiH and Hβ are presented. The results show that the particles contributing to film growth at the early stage of plasma are much higher in number than those in the stabilized state.