Publications by authors named "Martijn F J Vos"

2 Publications

  • Page 1 of 1

Reaction Mechanisms during Atomic Layer Deposition of AlF Using Al(CH) and SF Plasma.

J Phys Chem C Nanomater Interfaces 2021 Feb 10;125(7):3913-3923. Epub 2021 Feb 10.

Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.

Metal fluorides generally demonstrate a wide band gap and a low refractive index, and they are commonly employed in optics and optoelectronics. Recently, an SF plasma was introduced as a novel co-reactant for the atomic layer deposition (ALD) of metal fluorides. In this work, the reaction mechanisms underlying the ALD of fluorides using a fluorine-containing plasma are investigated, considering aluminum fluoride (AlF) ALD from Al(CH) and an SF plasma as a model system. Surface infrared spectroscopy studies indicated that Al(CH) reacts with the surface in a ligand-exchange reaction by accepting F from the AlF film and forming CH surface groups. It was found that at low deposition temperatures Al(CH) also reacts with HF surface species. These HF species are formed during the SF plasma exposure and were detected both at the surface and in the gas phase using infrared spectroscopy and quadrupole mass spectrometry (QMS), respectively. Furthermore, QMS and optical emission spectroscopy (OES) measurements showed that CH and CH F ( ≤ 3) species are the main reaction products during the SF plasma exposure. The CH release is explained by the reaction of CH ligands with HF, while CH F species originate from the interaction of the SF plasma with CH ligands. At high temperatures, a transition from AlF deposition to AlO etching was observed using infrared spectroscopy. The obtained insights indicate a reaction pathway where F radicals from the SF plasma eliminate the CH ligands remaining after precursor dosing and where F radicals are simultaneously responsible for the fluorination reaction. The understanding of the reaction mechanisms during AlF growth can help in developing ALD processes for other metal fluorides using a fluorine-containing plasma as the co-reactant as well as atomic layer etching (ALE) processes involving surface fluorination.
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http://dx.doi.org/10.1021/acs.jpcc.0c10695DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8016095PMC
February 2021

Atomic Layer Deposition of Cobalt Using H-, N-, and NH-Based Plasmas: On the Role of the Co-reactant.

J Phys Chem C Nanomater Interfaces 2018 Oct 5;122(39):22519-22529. Epub 2018 Sep 5.

Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.

This work investigates the role of the co-reactant for the atomic layer deposition of cobalt (Co) films using cobaltocene (CoCp) as the precursor. Three different processes were compared: an AB process using NH plasma, an AB process using H/N plasma, and an ABC process using subsequent N and H plasmas. A connection was made between the plasma composition and film properties, thereby gaining an understanding of the role of the various plasma species. For NH plasma, H and N were identified as the main species apart from the expected NH, whereas for the H/N plasma, NH was detected. Moreover, HCp was observed as a reaction product in the precursor and co-reactant subcycles. Both AB processes showed self-limiting half-reactions and yielded similar material properties, that is, high purity and low resistivity. For the AB process with H/N, the resistivity and impurity content depended on the H/N mixing ratio, which was linked to the production of NH molecules and related radicals. The ABC process resulted in high-resistivity and low-purity films, attributed to the lack of NH species during the co-reactant exposures. The obtained insights are summarized in a reaction scheme where CoCp chemisorbs in the precursor subcycle and NH species eliminate the remaining Cp in the consecutive subcycle.
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http://dx.doi.org/10.1021/acs.jpcc.8b06342DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6174421PMC
October 2018