Status and prospects of plasma-assisted atomic layer deposition

Processing at the atomic scale is becoming increasingly critical for state-of-the-art electronic devices for computing and data storage, but also for emerging technologies such as related to the internet-of-things, artificial intelligence, and quantum computing. To this end, strong interest in improving nanoscale fabrication techniques such as atomic layer deposition (ALD) has been present. New ALD processes are being sought continuously and particularly plasma-assisted processes are considered an enabler for a wide range of applications because of their enhanced reactivity. This review provides an update on the status and prospects of plasma-assisted ALD with a focus on the developments since the publication of the review by Profijt et al. [J. Vac. Sci. Technol. A 29, 050801 (2011)]. In the past few years, plasma ALD has obtained a prominent position in the field of ALD with (i) a strong application base as demonstrated by the breakthrough in high-volume manufacturing; (ii) a large number of established processes, out of which several are being enabled by the plasma step; and (iii) a wide range of plasma ALD reactor designs, demonstrating many methods by which plasma species can be applied in ALD processes. In addition, new fundamental insights have been obtained, for instance, with respect to plasma damage, on the effect of ions on the material properties and on the so-called redeposition effect. Regarding new and emerging developments, plasma ALD is expected to take a prominent position in the atomic-scale processing toolbox and will contribute to ongoing developments in area-selective deposition, controlled growth of 2D materials, and atomic layer etching.