Atomic layer deposition of tungsten and tungsten-based compounds using WCl5 and various reactants selected by density functional theory

Lee, Minyoung; Hidayat, Romel; Nandi, Dip K.; Kim, Tae Hyun; Kim, Yewon; Kim, Seongyoon; Lee, Wonjun; Kim, Soohyun

doi:10.1016/j.apsusc.2021.150373

Cited by 9 publications

(8 citation statements)

References 61 publications

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“…However, the higher quality film formation is confirmed when NH 3 plasma is used as a reactant in place of NH 3 molecules by thermal ALD. 27 This relatively high resistivity and XRD spectra indicate that the deposited WN x films would be more matched with WN rather than W 2 N, discussed in the next segment. The films deposited in N 2 + H 2 mixture plasma showed the most suitable performance because of the lowest resistivity (6210 μΩ-cm) and crystallinity of as-grown WN x film.…”

Section: Resultsmentioning

confidence: 88%

“…As stated in the introduction section, our group recently reported the thermal ALD process of the WN x process using the same W precursor, WCl 5 , and various reactants . In that study, TBH molecules could produce the amorphous tungsten carbide film with a small amount of N incorporation, and a crystalline ALD-W 2 N thin film was only possible using NH 3 molecules as the reactant under the same condition of 1000 cycles and 300 °C, whereas no deposition occurred with N 2 molecules.…”

Section: Resultsmentioning

confidence: 98%

“…In our previous study, H 2 plasma toward reducing WCl 5 produces W-metal deposition. 27 One can note that the selective deposition of WN x thin film by controlling the H 2 plasma in the N 2 + H 2 gas ratio showed a thickness of about ∼32 to 39 nm and attained the lowest resistivity (∼9800−1400 μΩ-cm) of the as-grown WN x film compared to using WF 6 and NH 3 5,16,17 or thermal ALD-WN x films with a metalorganic precursor (1500−4500 μΩ-cm). 18−20 Moreover, impurities such as oxygen and chlorine were also detected throughout the film.…”

Section: Properties Of Ald-wnmentioning

confidence: 99%

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Fluorine-free Plasma Enhanced Atomic Layer Deposited Ultrathin Tungsten Nitride Thin Films for Dual Diffusion Barrier Performance

Seo,

Mohapatra,

Bae

et al. 2023

ACS Appl. Nano Mater.

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A vacuum deposition technique in a highly narrow device is a critical issue for fabricating barrier layers in semiconductor devices. Though tungsten nitride (WN x ) thin films’ uniform and conformal thickness control can be achieved via atomic layer deposition (ALD), most ALD-WN x processes use fluorine-based precursors, resulting in high resistivity with low growth rate and corrosive and toxic F-containing impurities. This study underscores the importance of the plasma-enhanced ALD (PEALD) process for WN x films via a fluorine-free inorganic WCl5 precursor and critically optimizes the counter reactant ratio (N2 + H2 ratio of 1:1 to 1:10), temperature ranges (200∼325 °C), plasma mixture, plasma power, and postannealing condition process parameters. The as-grown WN x film properties and the impact of the plasma ratio on the WN phase, crystallinity, and stoichiometry were confirmed comprehensively by advanced transmission electron microscopy, spectroscopy, and diffraction techniques. Notably, secondary ion mass and photoelectron spectroscopies ensure uniformity and fewer impurity contents of O/Cl throughout the thickness of the WN x film. Significantly, the parent nanocrystalline hexagonal WN phase at a N2 + H2 ratio of 1:3 at 250 °C transformed to a crystalline cubic W2N phase with decreasing resistivity as the H2 ratio of total N2 + H2 mixture plasma gas increased. The postannealed (500 °C) deposited WN x film demonstrated the formation of a stable cubic phase, lowering the sheet resistance with increasing deposition temperature (film thickness) and plasma ratio. The as-deposited film’s diffusion barrier performance against Cu and Ru (∼4 nm) was evaluated to withstand up to 850 °C, revealing a promising dual diffusion barrier capability as interconnects in challenging shrinking semiconductor device structures.

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Section: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 98%

Section: Properties Of Ald-wnmentioning

confidence: 99%

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Fluorine-free Plasma Enhanced Atomic Layer Deposited Ultrathin Tungsten Nitride Thin Films for Dual Diffusion Barrier Performance

Seo,

Mohapatra,

Bae

et al. 2023

ACS Appl. Nano Mater.

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“…More specifically, tantalum-arsenide (TaAs) is the first experimentally discovered [36,37] WSM material and recent experiments have demonstrated growth of TaAs thin films via molecular beam epitaxy [38] and pulsed laser deposition [39]. Ge thin films have been deposited on metallic substrates via electron beam evaporation [40] and thin tungsten films have been grown using atomic layer deposition (ALD) [41]. Note that the ALD technique enables highly precise control of the layer thickness, making the ultrathin 5nm tungsten layer realization also feasible [42].…”

Section: Resultsmentioning

confidence: 99%

Broadband and wide angle nonreciprocal thermal emission from Weyl semimetal structures

Butler¹,

Argyropoulos²

2023

J. Opt. Soc. Am. B

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Nonreciprocal thermal emission is a cutting-edge technology that enables fundamental control over thermal radiation and has exciting applications in thermal energy harvesting. However, thus far one of the foremost challenges is making nonreciprocal emission operate over a broad wavelength range and for multiple angles. In this work, we solve this outstanding problem by proposing three different types of structures that always utilize only one Weyl semimetal (WSM) thin film combined with one or two additional dielectric or metallic layers and terminated by a metallic substrate. First, a tradeoff relationship between the magnitude and bandwidth of the thermal nonreciprocity contrast is established based on the thickness of the WSM film. Then, the bandwidth broadening effect is demonstrated via the insertion of a dielectric spacer layer that can also be fine-tuned by varying its thickness. Finally, further control on the resulting strong nonreciprocal thermal radiation is demonstrated by the addition of a thin metallic layer in the proposed few layer designs. The presented composite structures work for a broad frequency range and for multiple emission angles, resulting in highly advantageous properties for various nonreciprocal thermal radiation applications. Moreover, the proposed designs do not require any patterning and can be experimentally realized by simple deposition fabrication methods. They are expected to aid in the creation of broadband nonreciprocal thermal emitters that can find applications in new energy harvesting devices.

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“…Quantum chemical simulations can be a powerful tool for optimizing molecular structures of reactants, providing insights into the energetics, structure, and reactivity of the molecules at the atomic level. Regarding theoretical elucidation of the surface chemistry and molecular design of the reactants for thin-film deposition processes, there has been considerable efforts on the metal precursors. − However, the chemical reaction mechanism of the counter-reactant step, especially including those involving organic reactants, is far less understood. − …”

Section: Introductionmentioning

confidence: 99%

Rational Molecular Design for Non-aqueous Atomic Layer Deposition of Zinc Oxide

et al. 2023

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Zinc oxide (ZnO) is a transparent wide band gap semiconductor material with various possible applications in form of thin films. Most previous studies on atomic layer deposition (ALD) of ZnO thin films utilized a few well-known processes with diethylzinc (DEZ) and counter-reactants such as H2O and O3. However, O3 and H2O reactants have relatively strong reactivity, so that they are not suitable for substrates sensitive to oxidation. Therefore, development of milder non-aqueous alternative ALD process for ZnO is highly desired. In this study, we introduce ALD of ZnO using alcohols with theoretically optimized molecular structure. To discover suitable alcohol reactants for ZnO ALD, reaction pathways and reactivity between various types of alcohol reactants with surface-ethyl groups were evaluated through density functional theory calculations. It was found that unsaturated allylic alcohols would have the lowest activation energy for ZnO ALD via an allylic rearrangement mechanism. Experimental, novel ALD processes for ZnO using DEZ with alcohol as oxygen sources are set up. Ethanol as a typical simple alcohol is compared to 2-methyl-3-buten-2-ol (MBO) as an alcohol with optimal molecular structure setup. ALD ZnO films using MBO showed processes and material properties comparable to those of H2O-ALD ZnO. ZnO thin films as transparent conducting oxide could be obtained, and device performances of thin-film transistors based on alcohol-ALD processes are evaluated.

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Atomic layer deposition of tungsten and tungsten-based compounds using WCl5 and various reactants selected by density functional theory

Cited by 9 publications

References 61 publications

Fluorine-free Plasma Enhanced Atomic Layer Deposited Ultrathin Tungsten Nitride Thin Films for Dual Diffusion Barrier Performance

Fluorine-free Plasma Enhanced Atomic Layer Deposited Ultrathin Tungsten Nitride Thin Films for Dual Diffusion Barrier Performance

Broadband and wide angle nonreciprocal thermal emission from Weyl semimetal structures

Rational Molecular Design for Non-aqueous Atomic Layer Deposition of Zinc Oxide

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