Recent developments in plasma assisted physical vapour deposition

Recent developments in plasma assisted physical vapour deposition (PAPVD) processes are reviewed. A short section on milestones in advances in PAPVD covering the time period from 1938 when the first PAPVD system was patented to the end of the 1980s is followed by a more detailed discussion of some more recent advances, most of which have been related to increases in plasma density. It has been demonstrated that the state of the art PAPVD processes operate in a plasma density range of 10¹¹ to 10¹³ cm^-3. In this range a substantial fraction of the plasma consists of ionized film forming species. Hence, the energy of the condensing film forming species can be directly controlled, as opposed to utilizing indirect energy control with, for example, ionized inert gas bombardment. For a large variety of applications ranging from ceramic film synthesis at conditions far from thermodynamic equilibrium to state of the art metallization technology, such direct energy control of the condensing film forming species is of critical importance, and offers the possibility to engineer the coating microstructure and hence the coating properties.