In this paper, the emerging role of ionic species in plasma assisted chemical deposition processes is discussed in details 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 (PECVD) and Plasma Enhanced Atomic Layer Deposition (PEALD) 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 its 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.

TiN/Gd:HfO2/TiN metal/ferroelectric/metal structures were elaborated in one batch by plasma enhanced atomic layer deposition. The crystal structure and ferroelectric properties of 12-nm-thick Gd-doped HfO2 thin films are investigated. The modulation of the Gd content within the HfO2 layer leads to a subsequent variation of crystalline phases; predominance of the orthorhombic phase correlates with a maximum 2·Pr value of 30 μC/cm2 for 1.8% of Gd doping as well as a ferroelectric polarization switching endurance up to 7 × 109 cycles. These remarkable properties of Gd:HfO2 material compared to previous works are likely the consequence of nonexposure to air of metal/insulator interfaces during stack deposition, preventing their oxidation and/or carbon contamination.

In this paper, we present a topographically Selective Deposition process which allows the vertical only coating of three-dimensional (3D) nano-structures. This process is based on the alternate use of plasma enhanced atomic layer deposition (PEALD) and sputtering carried out in a PEALD reactor equipped with a radio-frequency substrate biasing kit. A so-called super-cycle has been conceived, which consists of 100 standard deposition cycles followed by an anisotropic argon sputtering induced by the application of a 13.56 MHz biasing waveform to the substrate holder in the PEALD chamber. This sputtering step removes the deposited material on horizontal surfaces only, and the sequential deposition/etch process allows effective deposition on vertical surfaces only. Thus, it opens up a route for topographically selective deposition, which can be of interest for the fabrication of 3D vertical Metal-Insulator-Metal devices.