Study on plasma cleaning of surface contaminants on pure copper

Abstract

To demonstrate the relationship between the type of working gas and the efficiency of plasma cleaning, the kinetic energy of the incident ions was controlled by adjusting the bias, and the effect of different ion sources on the sputtering yield under the same bias was compared. The plasma flow generated by glow discharge was used to clean the sample surface to evaluate the plasma cleaning efficiency. Scanning electron microscope (SEM), x-ray photoelectron spectroscopy (XPS), x-ray Powder Diffraction (XRD), Ultraviolet-visible Spectrophotometer (UV), and Surface Profiler were used to characterize the surface morphology, element types, phase composition, specular reflectance, and three-dimensional (3D) morphology before and after plasma cleaning. The results show that the sputtering yield increases with the increase of bias, and when the bias value is lower than 400 V, the mass of the samples has almost no change before and after cleaning. It takes more energy to remove the surface oxide than the pure metal copper. The results also show that argon plasma has a better effect on removing pollutants on the sample surface than nitrogen plasma. However, a long time of plasma cleaning is often accompanied by re-deposition. The changes in copper reflectance induced by plasma cleaning are also discussed.

Keywords

• copper
• plasma
• roughness
• morphology