Low Temperature Deposition of Cu Thin Film on Polyimide Using RF-driven Atmospheric Pressure Plasma Jet in Nitrogen Atmosphere

For fabrication of future flexible electronic devices, Cu films on polyimide substrate were prepared by atmospheric pressure plasma (APP) jet. The plasma jet was driven by an radio frequency (RF, 13.56 MHz), and ignited by applying RF power of 300 W to the coil after plasma-gas introduction (Ar: 1000 sccm, H-2: 10 sccm). A copper water-cooling heat sink is used as a substrate platform to avoid the thermal damage of polyimide by APP jet. To prevent the oxidation of deposited film, the effects of adding H-2 into Ar plasma gas and replacing air to nitrogen atmosphere were studied. Stylus profiler was used to measure a thickness of each film. The surface morphology and roughness of the Cu films were measured by AFM and SEM. The characterization of Cu films on polyimide was investigated with XPS.