Film conformality and extracted recombination probabilities of O atoms during plasma-assisted atomic layer deposition of SiO2, TiO2, Al2O3, and HfO2

Karsten Arts, Mikko Utriainen, R.L. Puurunen, Erwin Kessels (Corresponding author), Harm Knoops (Corresponding author)

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Surface recombination of plasma radicals is generally considered to limit film conformality during plasma-assisted atomic layer deposition (ALD). Here, we experimentally studied film penetration into high-aspect-ratio structures and demonstrated that it can give direct information on the recombination probability r of plasma radicals on the growth surface. This is shown for recombination of oxygen (O) atoms on SiO2, TiO2, Al2O3, and HfO2 where a strong material dependence has been observed. Using extended plasma exposures, films of SiO2 and TiO2 penetrated extremely deep up to an aspect ratio (AR) of ∼900, and similar surface recombination probabilities of r = (6 ± 2) × 10–5 and (7 ± 4) × 10–5 were determined for these processes. Growth of Al2O3 and HfO2 was conformal up to depths corresponding to ARs of ∼80 and ∼40, with r estimated at (1–10) × 10–3 and (0.1–10) × 10–2, respectively. Such quantitative insight into surface recombination, as provided by our method, is essential for modeling radical-surface interaction and understanding for which materials and conditions conformal film growth is feasible by plasma-assisted ALD.
Original languageEnglish
Pages (from-to)27030-27035
Number of pages6
JournalJournal of Physical Chemistry C
Issue number44
Publication statusPublished - 7 Nov 2019


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