Thermal atomic layer deposition of metallic Ru using H2O as a reactant

Nguyen, Chi Thang; Yoon, Jeong Hyun; Khan, Rizwan; Shong, Bonggeun; Lee, Han‐Bo‐Ram

doi:10.1016/j.apsusc.2019.05.242

Cited by 20 publications

(28 citation statements)

References 42 publications

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“…Another family of metal organics with bridge-bonded ligands used in chemical film deposition applications is diketonates. The most common ligands used in this case are the simplest acetylacetonate (acac) − and hexafluoroacetylacetonate (hfac) − moieties, but other diketonates with larger side chains are also known. ,− In many of the reported uses of these compounds the final target has been a metal oxide film, but some examples are also available for the growth of metallic films with these precursors, especially with late transition metals. ,− Although the studies available to date suggest that diketonates may be less reactive on surfaces than amidinates, they are still prone to fragmentation upon thermal activation.…”

Section: Resultsmentioning

confidence: 96%

Thermal Chemistry of Metal Organic Compounds Adsorbed on Oxide Surfaces

et al. 2019

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The thermal chemistry of several metal organic compounds with amidinate, diketonate, or cyclopentadienyl (Cp) ligands on oxide surfaces, mainly on silicon dioxide but also on aluminum oxide, was studied by using surface sensitive techniques, including temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), reflection–absorption infrared spectroscopy (RAIRS), and static secondary ion mass spectrometry (SSIMS), and those studies were complemented with quantum mechanics calculations. With the amidinates, TPD experiments revealed complex decomposition pathways, starting with a ligand-exchange step with OH surface groups. That is followed by migration of the remaining ligands from the metal center to the surface, where decomposition occurs mainly via bond scission at the terminal alkyl groups and β-hydride elimination steps to produce the corresponding olefins. At that stage, XPS data show that the metal is partially, but not completely, reduced, indicating a partially ionic metal–oxygen surface bond. The diketonates display only limited reactivity on silica, again via an initial ligand exchange step, but much higher reactivity is seen on alumina, where subsequent decomposition and olefin production are observed. The Cp ligands proved to be the most stable, hindering in fact the effective adsorption of these metal organic compounds unless prior activation in the gas phase via electron-impact excitation is carried out. After adsorption, the Cp proved to be quite sturdy, surviving long exposures to outside atmospheres (as shown by SSIMS). They can, however, be protonated (deuterated) upon high-temperature exposure to H2O (D2O). All this chemistry is discussed in general terms and contrasted with known reactivity in solution.

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Section: Resultsmentioning

confidence: 96%

Thermal Chemistry of Metal Organic Compounds Adsorbed on Oxide Surfaces

et al. 2019

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“…Figure shows the top view images of DFT-optimized adsorption structures of Carish and TMA. On the pure metallic Ru substrate, adsorption of the Carish precursor was found to occur dissociatively even without presence of H or OH on the surface, as shown in the chemical equation below: On the other hand, on oxide subrates with OH groups as in the current study, the precursor can be expected to partially lose its ligands. , The heteroleptic Carish precursor is expected to adsorb via losing CO ligands as the byproduct, retaining the diketonate ligands and forming dative bonds with OH groups ( E ads = +1.24 eV, chemical equation , Figure a). While it is also possible to form another adsorption structure, via protonation of the diketonate ligands, retention of CO, and formation of direct Ru–O bonds, such a structure is highly endothermic ( E ads = +2.39 eV, chemical equation , not shown) and, thus, ignored. For adsorption of TMA, the Al atom of TMA was adsorbed on the O atom of the surface hydroxyl (−OH). , While TMA is known to produce a mixture of −Al(CH 3 ) and −Al(CH 3 ) 2 upon adsorption onto the substrate surface, ,− in the interest of clarity in the discussion, we have assumed −Al(CH 3 ) to be the only surface product of TMA ( E ads = −3.11 eV, chemical equation , Figure b). Then, coadsorption of Carish and TMA as in the C-T and T-C sequences is considered.…”

Section: Resultsmentioning

confidence: 57%

“…Prior to the ALM experiments, we used the Carish and TMA precursors and H 2 O as the counter reactant to investigate the growth characteristics of Ru and Al 2 O 3 in the ALD system. One Ru ALD growth cycle was composed of a Carish pulse (5 s)a N 2 purge (7 s)a H 2 O pulse (5 s)and a N 2 purge (7 s) at 283 °C . One Al 2 O 3 ALD growth cycle was composed of a TMA pulse (1 s)a N 2 purge (30 s)a H 2 O pulse (1 s)and a N 2 purge (30 s) at 283 °C.…”

Section: Methodsmentioning

confidence: 99%

“…In this study, RuAlO x ALM using Ru and Al 2 O 3 ALD was employed as a model system. Owing to its electrical and chemical stability, Ru ALD has been applied to liner materials in 3-dimensional Si nanodevice interconnects. , The modulation of Ru with Al 2 O 3 , a well-known amorphous atomic insulator, could improve the Ru ALD diffusion barrier. , In our previous work, metallic Ru was obtained using an H 2 O counter reactant and an Ru precursor, dicarbonyl- bis (5-methyl-2,4-hexanediketonato)Ru(II) (Carish) . In this work, trimethylaluminum (TMA) and Carish Ru precursors were employed.…”

Section: Introductionmentioning

confidence: 99%

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Atomic Layer Modulation of Multicomponent Thin Films through Combination of Experimental and Theoretical Approaches

Nguyen

Cheon

et al. 2021

Chem. Mater.

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We proposed the concept of atomic layer modulation (ALM) based on precursor chemical reactivities and steric hindrance effects to fabricate multicomponent nanofilms. Because ALM employs consecutive precursor exposures followed by exposure to a counter reactant, the composition of ALM films is determined by the molecular size and chemical reactivities of the precursors. For the demonstration, dicarbonyl-bis(5-methyl-2,4-hexanediketonato)Ru(II) (Carish) and trimethylaluminum (TMA) were used as Ru and Al precursors, respectively, and H2O was used as the counter reactant. Prior to the experiments, the chemical reactivity and sterically hindered physisorption of the Ru and Al precursors were theoretically calculated using density functional theory (DFT) and Monte Carlo (MC) simulations, respectively. The transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) results were highly consistent with the theoretical results, and the growth characteristics were well explained by the MC- and DFT-based reaction models. We believe that ALM could be extended to other material systems, thereby providing a different method of fabricating multicomponent nanofilms for various applications including semiconductors and nanodevices.

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“…Fortunately, the advance of density functional theory (DFT) provides an alternative way to get that information. We ,− and others ,− have embarked in complementing studies on the mechanism of metalorganics on surfaces with this type of theoretical approach.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Study of the Adsorption and Dissociation of Copper(I) Acetamidinates on Ni(110): The Effect of the Substrate

et al. 2020

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In order to assess the role of metal substrates on the thermal chemistry of adsorbed acetamidinate metalorganic compounds, we have studied the surface chemistry of copper-(I)−N,N′-dimethylacetamidinate on Ni(110) using density functional theory and contrasted it with similar calculations we previously carried out on Cu(110). At low coverages, it was found that, in its most stable configuration, the molecular adsorption of copper(I)−N,N′-dimethylacetamidinate dimers occurs with the Cu atoms occupying surface hollow sites. The ligands reorient away from those metal centers, and the N atoms develop new direct bonds with surface Ni atoms. However, this configuration is not stable and decomposes by losing both ligands to the surface. In the final state, the two ligands bind via their N atoms to Ni sites one lattice space away from the sites where the Cu atoms remain, with their molecular planes perpendicular to that of the surface. This is in contrast with what happens in the case of adsorption on Cu(110), where the Cu atoms from the metalorganic complex still occupy hollow sites but where only one of the ligands breaks away and binds directly to the surface; the other remains on top of the two Cu ions. In terms of the energetics of adsorption and decomposition, the reactions on Ni(110) are much more exothermic than on Cu(110). Further analysis of the distribution of charge within the adsorbates shows a minor reduction of the Cu atoms of the dimer upon interaction with the surface; full reduction to metallic copper is complete only when both ligands have fully migrated to their new Ni surface sites.

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Thermal atomic layer deposition of metallic Ru using H2O as a reactant

Cited by 20 publications

References 42 publications

Thermal Chemistry of Metal Organic Compounds Adsorbed on Oxide Surfaces

Thermal Chemistry of Metal Organic Compounds Adsorbed on Oxide Surfaces

Atomic Layer Modulation of Multicomponent Thin Films through Combination of Experimental and Theoretical Approaches

Density Functional Theory Study of the Adsorption and Dissociation of Copper(I) Acetamidinates on Ni(110): The Effect of the Substrate

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