Critical issues in plasma-assisted vapor deposition processes

The currently used plasma-assisted vapor deposition processes are reviewed. They are analyzed in terms of the three steps in deposition processes, i.e. generation of the depositing species, transport from source to substrate, and film growth on the substrate. The role of the plasma in each of the steps for the various processes is discussed. All processes involve two sets of parameters: the plasma parameters and the process parameters. These parameters couple to a greater or lesser degree in each of the basic processes, which reflects their versatility. The roles of plasma volume chemistry and plasma diagnostics are discussed. It is clear that a deeper basic understanding of plasma-assisted deposition processes necessitates a much greater volume of work on plasma diagnostics coupled with theoretical estimates. The influence of ion bombardment on the structure, composition, and properties of the films is considered. Hybrid processes which attempt to circumvent the somewhat deleterious intercoupling of the plasma and process parameters are briefly discussed