Film Conformality and Extracted Recombination Probabilities of O Atoms during Plasma-Assisted Atomic Layer Deposition of SiO2, TiO2, Al2O3, and HfO2

Research output: Contribution to journalArticleScientificpeer-review


Research units

  • Eindhoven University of Technology
  • VTT Technical Research Centre of Finland
  • Oxford Instruments Group Plc


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 â900, 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 â80 and â40, 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
MoE publication typeA1 Journal article-refereed

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