Surface morphology of a Cu substrate flattened by a 2″ photoemission-assisted ion beam source

Photoemission-assisted plasma irradiation of a 2′ Cu substrate was performed to clarify the effect of ion impingement on the substrate. With the use of a photoemission-assisted plasma apparatus, the photoemission-assisted plasma was evaluated by optical emission spectroscopy and discharge characteristics. The density ratio of Ar ions and atoms increases with increasing the bias voltage of photoemission-assisted plasma. Changes in the surface morphology of the substrate were investigated using atomic force microscopy. Sufficient ion density can be obtained in photoemission-assisted Townsend discharge, and surface roughness of the Cu substrate decreased as the plasma irradiation time increased. This result indicates that ion impingement from photoemission-assisted Townsend plasma can sputter the metal surfaces, leading to a decrease in surface roughness.