Relative importance of bombardment energy and intensity in ion plating

For ion plating and similar plasma assisted physical vapor deposition processes, the relative significance of bombardment energy and intensity during film growth is poorly understood in relation to their effects on certain coating properties. In this article, we report on the results of a study on the micro structural properties of copper coatings deposited by a thermionically supported ion plating system with an electon beam evaporation source. By carefully selecting the deposition conditions, analysis of the coatings has provided the following conclusions: First, provided that a critical bombardment energy is exceeded, increasing bombardment intensity is more important than increasing the energy at the growing coating surface to attain maximum coating densification for minimum bombardment power. For copper coatings, the critical energy is approximately 200 eV. Second, we have identified sputtering as the main mechanism responsible for material redistribution during coating growth. We suggest that coating densification resulting from energetic bombardment may be characterized in a structure zone model by a parameter representing the proportion of arriving material which is sputtered during deposition.