Surface Modification of Cu Native Oxide: Ag Displacement for Homogeneous Layering

Cu's electrical and thermal conductivity makes it a vital material in various industrial applications, but its susceptibility to oxidation under ambient conditions can compromise performance, particularly in the semiconductor industry. This study presents an innovative surface modification technique to inhibit the growth of native oxide on Cu prior to Ag coating to enhance a galvanic replacement (GR) reaction under good adhesion between Ag and Cu. Ag-coated Cu electrodes are effective in removing the surface oxide on Cu and acting as deformable and low-resistance Cu interconnects. The surface modification process utilizes vacuum ultraviolet (VUV) treatment in an ethanol atmosphere, forming a stable, hydroxylated surface layer that minimizes reoxidation before Ag deposition. X-ray photoelectron spectroscopy (XPS) confirmed the effective suppression of reoxidation, and scanning electron microscopy (SEM) revealed a homogeneous Ag coating with optimal surface coverage. This methodology significantly enhances the oxidation resistance of Cu.