Ionization in plasma-assisted physical vapour deposition systems

In this paper we discuss recent developments in plasma-assisted physical vapour deposition processes, extending on earlier work, and emphasizing the characteristics of the various enhanced ionization systems. The non-uniform natures of the ion and vapour distributions in these systems are discussed in the context of theoretical models and empirical studies covering these effects. The ionization efficiencies of the successful commercial systems are shown to be over 3.5%, although caution is necessary in determining the location of samples relative to sources which themselves enhance ionization, such as the unbalanced magnetron or arc source, as inhomogenous or “beamy” plasmas can be generated with consequential ionization variations. Nevertheless, with appropriate equipment design full-scale mass production of coated components can be achieved.