Extinction of Large Droplets in Ion-Beam Ablation Plasma Produced by Ion-Beam Evaporation

Abstract

The extinction of large droplets in ablation plasma produced by intense pulsed ion-beam evaporation (IBE) has been proposed to improve the surface morphology of Al thin films on Si substrates. After the ion-beam irradiation of an Al target, a lot of spherical objects with diameters of approximately 20 to 100 µm were observed on the Al target surface, they are considered to be a possible origin of droplets commonly observed on Al thin films. However, the number of large droplets decreased with increasing distance between the Al target and Si substrate. The following model was considered to explain the obtained results. When a spherical object flies in the ablation plasma, it seems that the object fragments into small pieces or is evaporated. As a result, the number of large droplets decreases with increasing flight distance.