In vacuo studies on reaction mechanisms in ALD processes of ruthenium and platinum films

Nieminen, Heta-Elisa; Putkonen, Matti; Ritala, Mikko

doi:10.1016/j.apsusc.2023.159015

Cited by 3 publications

(2 citation statements)

References 50 publications

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“…The sample is mounted on a transferring rod for fast exchange between these two chambers without exposure to the outside atmosphere, and also to cool down and/or resistively heat it to any temperature between 150 and 1100 K. We have used this type of equipment extensively already, for studies of both catalytic [89][90][91] and ALD [92][93][94] systems. Instruments designed with a similar philosophy have been recently reported by other research groups [95][96][97]. It should be noted that the characterization of surfaces in situ under reaction conditions has been greatly advanced by the catalysis community [80,98,99], and much of what has been developed there can be directly transfer to the study of ALD reactions.…”

Section: Mechanistic Studies Experimental Approachmentioning

confidence: 99%

“…A more viable option for the removal of the organic material deposited in the first half of metal ALD cycles is to use an oxidizing agent as the co-reactant in the second half. This approach is particularly promising for cases where the ALD temperature is high enough to lead to the initiation of the decomposition of the ligands in the metalorganic precursors used in the first ALD half, because, as indicated above, such chemistry often leads to the formation of irreversibly and hard-tohydrogenate surface species that then need to be burned to CO 2 and H 2 O (and possibly CO) [96]. Molecular oxygen is often used in these cases [20,148,149], but here a problem similar to that with H 2 emerges because the O=O double bond in O 2 is hard to activate; relatively high temperatures are required for that, and such high temperatures are in general to be avoided in ALD.…”

Section: Selection and Role Of Co-reactantmentioning

confidence: 99%

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The surface chemistry of the atomic layer deposition of metal thin films

Zaera

2024

Nanotechnology

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In this perspective we discuss the progress made in the mechanistic studies of the surface chemistry associated with the atomic layer deposition (ALD) of metal films and the usefulness of that knowledge for the optimization of existing film growth processes and for the design of new ones. Our focus is on the deposition of late transition metals. We start by introducing some of the main surface-sensitive techniques and approaches used in this research. We comment on the general nature of the metallorganic complexes used as precursors for these depositions, and the uniqueness that solid surfaces and the absence of liquid solvents bring to the ALD chemistry and differentiate it from what is known from metalorganic chemistry in solution. We then delve into the adsorption and thermal chemistry of those precursors, highlighting the complex and stepwise nature of the decomposition of the organic ligands that usually ensued upon their thermal activation. We discuss the criteria relevant for the selection of co-reactants to be used on the second half of the ALD cycle, with emphasis on the redox chemistry often associated with the growth of metallic films starting from complexes with metal cations. Additional considerations include the nature of the substrate and the final structural and chemical properties of the growing films, which we indicate rarely retain the homogeneous 2D structure often aimed for. We end with some general conclusions and personal thoughts about the future of this field.

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Section: Mechanistic Studies Experimental Approachmentioning

confidence: 99%

Section: Selection and Role Of Co-reactantmentioning

confidence: 99%

The surface chemistry of the atomic layer deposition of metal thin films

Zaera

2024

Nanotechnology

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Time-resolved ambient pressure x-ray photoelectron spectroscopy: Advancing the operando study of ALD chemistry

Jones,

Kokkonen,

Eads

et al. 2025

Surface Science

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Ambient pressure x-ray photoelectron spectroscopy study on the initial atomic layer deposition process of platinum

Kokkonen,

Nieminen,

Rehman

et al. 2024

Journal of Vacuum Science &Amp; Technology A

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The initial adsorption of MeCpPtMe3 is investigated using synchrotron-based ambient pressure x-ray photoelectron spectroscopy (XPS). The experiments are done on a native oxide-covered Si substrate. In addition, a reaction with O2 and the created Pt surface was investigated. Inspiration for the reaction studies was found from atomic layer deposition of metallic Pt, process that uses the same compounds as precursors. With time-resolved XPS, we have been able to observe details of the deposition process and especially see chemical changes on the Pt atoms during the initial deposition of the Pt precursor. The change of the binding energy of the Pt 4f core level appears to occur on a different timescale than the growth of the active surface sites. The very long pulse of the Pt precursor resulted in a metallic surface already from the beginning, which suggest chemical vapor deposition-like reactions occurring between the surface and the precursor molecules in this experiment. Additionally, based on the XPS data measured after the Pt precursor pulse, we can make suggestions for the reaction pathway, which point toward a scenario that leaves carbon from the MeCpPtMe3 precursor on the surface. These carbon species are then efficiently removed by the subsequent coreactant pulse, leaving behind a mostly metallic Pt film.

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In vacuo studies on reaction mechanisms in ALD processes of ruthenium and platinum films

Cited by 3 publications

References 50 publications

The surface chemistry of the atomic layer deposition of metal thin films

The surface chemistry of the atomic layer deposition of metal thin films

Time-resolved ambient pressure x-ray photoelectron spectroscopy: Advancing the operando study of ALD chemistry

Ambient pressure x-ray photoelectron spectroscopy study on the initial atomic layer deposition process of platinum

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