Plasma deposition—Impact of ions in plasma enhanced chemical vapor deposition, plasma enhanced atomic layer deposition, and applications to area selective deposition

In this paper, the emerging role of ionic species in plasma assisted chemical deposition processes is discussed in detail for commemorating the Career of John Coburn, who studied the role of ionic species in plasma etching processes forty years ago. It is shown that, in both plasma enhanced chemical vapor deposition and plasma enhanced atomic layer deposition processes, plasma ions can play a major role in tuning a wide range of physical properties of thin films. In both processes, the possibility of extracting plasma ions with a tunable incident kinetic energy driven on the substrate surface is shown to provide a valuable additional degree of freedom in plasma processing. While a too large incident kinetic energy of plasma ions may have damaging effects linked to surface sputtering and atomic peening, a relatively low energy ion bombardment ensures a substantial improvement of thin film purity and the effective tuning of their microstructural properties. This phenomenon is attributed to the synergetic effect boosting momentum transfer and chemical reactivity among radicals and ionic plasma species, which, in turn, modulates plasma-surface interactions. Taking advantage of these tunable physical properties opens up the way to a large array of pathways for selective deposition processes in both 2D and 3D nanoscale microstructures.