The effects of decomposition of CpZr(NMe2)3 on atomic layer deposition for high-k ZrO2 thin films

Choi, Eun-Mi; Kim, Hayeong; Maeng, Seonjeong; Lee, Jaebaek; Kim, Dae-Hwan; Heo, Kyuyoung; Yun, Ju‐Young

doi:10.1016/j.mtcomm.2022.104008

Cited by 5 publications

(4 citation statements)

References 24 publications

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“…For every precursor, an experimental value of P vap at some temperature was collected from open sources. − The diverse chemical structures and a broad range of P vap values, covering more than 6 orders of magnitude, pose a challenge to the automatic force field generation procedure and simulation protocols. This provided a solid basis for validating our approach.…”

Section: Resultsmentioning

confidence: 99%

Ab Initio Prediction of Vapor Pressure for Diverse Atomic Layer Deposition Precursors

Odinokov,

Son,

Yakubovich

et al. 2024

J. Chem. Theory Comput.

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Understanding the saturated vapor pressure (P vap ) is vital for evaluating atomic layer deposition (ALD) precursors, as it directly influences the ALD temperature window and, by extension, the processability of compounds. The early estimation of vapor pressure ranges is crucial during the initial stages of novel precursor design, reducing the reliance on empirical synthesis or experimentation. However, predicting vapor pressure through computer simulations is often impeded by the scarcity of suitable empirical force fields for molecular dynamics simulations. This challenge is further compounded by the diverse chemical substances and the introduction of new elements into modern ALD processes, necessitating robust force fields that can accommodate metals, organics, and halides. In response, this study introduces a novel approach utilizing a quantum mechanically derived force field for the prediction of vapor pressure across a wide spectrum of potential ALD precursors. This approach enables the creation of system-specific force fields through parametrization based on ab initio calculations for a single molecule. We develop a comprehensive workflow to simulate both liquid and gaseous equilibrium phases, allowing the calculation of vapor pressure across a wide temperature range. Our methodology has been validated with a diverse set of ALD precursors, demonstrating its robustness in predicting P vap at specified temperatures. The approach yields a Pearson's correlation coefficient (R 2 ) greater than 0.9 on a logarithmic scale and a root-meansquared deviation in self-solvation-free energies as low as 1.3 kcal mol −1 . This innovative workflow, which does not require any prior experimental data, marks a significant advancement in the computer-aided design of novel ALD precursors, paving the way for accelerating developments in technology.

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Section: Resultsmentioning

confidence: 99%

Ab Initio Prediction of Vapor Pressure for Diverse Atomic Layer Deposition Precursors

Odinokov,

Son,

Yakubovich

et al. 2024

J. Chem. Theory Comput.

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“…In addition, the ligands in heteroleptic precursors undergo thermal decomposition or ligand redistribution reactions upon long time heating in the precursor container for precursor vapor supply into the ALD chamber to generate the eliminated ligands and the reaction byproducts. 21 It is thus plausible that these compounds afford mixtures of heteroleptic Hf(IV) precursors by ligand redistribution reactions. Given these facts, we consider that the heteroleptic precursor is not always the best structure.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Thus, heteroleptic precursor manufacturing costs have been gradually rising compared to those of homoleptic precursors. In addition, the ligands in heteroleptic precursors undergo thermal decomposition or ligand redistribution reactions upon long time heating in the precursor container for precursor vapor supply into the ALD chamber to generate the eliminated ligands and the reaction byproducts . It is thus plausible that these compounds afford mixtures of heteroleptic Hf(IV) precursors by ligand redistribution reactions.…”

Section: Introductionmentioning

confidence: 99%

Atomic Layer Deposition of HfO₂ Films Using Tetrakis(1-(N,N-dimethylamino)-2-propoxy)hafnium [Hf(dmap)₄] for Advanced Gate Dielectrics Applications

Nishida,

Katayama,

Matsuo

2023

ACS Appl. Nano Mater.

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Atomic layer deposition (ALD) of HfO2 thin films was studied by using a novel Cl-free hafnium ALD precursor: tetrakis(1-(N,N-dimethylamino)-2-propoxy)hafnium [Hf(dmap)4]. This precursor is a liquid at room temperature and has been shown by differential scanning calorimetry (DSC) analysis to be stable at temperatures as high as 371 °C. Compared with the conventional Hf precursor tetrakis(ethylmethylamido)hafnium(IV) (TEMAH), Hf(dmap)4 exhibits a substantially greater decomposition temperature because of its alkoxide structure. Hf(dmap)4 is a volatile compound that shows a very clean thermogravimetry curve without decomposition or residue formation at 10 Torr. We performed ALD of HfO2 using Hf(dmap)4 with an oxidant of either O3 or H2O as an oxidant. As the wafer temperature was increased from 250 to 400 °C, the film growth rate slightly increased from 0.35 to 0.55 Å/cycle. Therefore, Hf(dmap)4 can be used for ALD at higher deposition temperatures than for TEMAH. However, the film growth rate was lowered by the sterically hindered ligand structure of the precursor. We evaluated the saturation behavior of the growth rate in experiments in which the Hf(dmap)4 supply time was varied from 5 to 30 s. As a result, a constant film growth rate was observed because of ALD saturation when the precursor supply time was 10 s or longer in the temperature range 350–400 °C. This result indicates that Hf(dmap)4 was not decomposed and behaved as an ALD precursor at 400 °C. We concluded that Hf(dmap)4 is a promising precursor for high-temperature ALD of HfO2 film for gate dielectrics, high-K capacitors, and HfO2-based ferroelectrics.

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“…These precursors, however, sometimes have drawbacks such as halide contamination and low stabilities in the case of the halide and alkoxides, respectively. Consequently, heteroleptic precursors including more than one type of ligands such as cyclopentadienyl (Cp)-alkoxides and Cp-alkylamides are developed, to enhance the thermal stability of precursors of the ALD high-k oxides. − When ozone is used as the oxygen source, ALD using zirconium and hafnium Cp-alkylamide precursors shows high growth per cycle (GPC), ranging from 0.8 to 0.9 Å per cycle, and the deposited films mostly possessed low levels of nitrogen and carbon contamination. Especially, ZrO 2 and HfO 2 films deposited using CpZr(N(Me 2 ) 3 and CpHf(N(Me 2 ) 3 precursors (Me = CH 3 ) and ozone have shown improved film density and electrical performance, possibly due to the deposition temperatures being as high as 350 °C.…”

Section: Introductionmentioning

confidence: 99%

Role of Cyclopentadienyl Ligands of Group 4 Precursors toward High-Temperature Atomic Layer Deposition

et al. 2022

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Deposition of high-k dielectric thin films is essential for manufacturing modern electronic devices. Atomic layer deposition (ALD) is an attractive technology for depositing high-k materials because it exhibits conformality and facilitates thickness control of the films at the atomic level. It has been suggested that high-temperature ALD can enhance the material properties of the deposited films such as density and crystallinity, for which the development of thermally stable precursors that deliver the metallic element is required. Heteroleptic titanium (Ti), zirconium (Zr), and hafnium (Hf) precursors containing amido and cyclopentadienyl (Cp) ligands have recently been introduced, with some demonstrating improved thermal stability. However, the mechanism behind the improved thermal stability of these precursors remains unclear. This research employs density functional theory (DFT) calculations to elucidate the role of Cp ligands of group 4 (Ti, Zr, Hf) precursors for high-temperature ALD. The surface adsorption reactions of the precursors on oxide surfaces are suggested to be facile. For most precursors, one or two ligands are thought to exist after chemical adsorption. Cp ligands, in particular, are expected to persist on the surface, whereas amido ligands are more easily eliminated during adsorption. The decomposition of the precursor after adsorption on the surface then is considered, for which the thermal stability is significantly enhanced by introducing the Cp ligand. Furthermore, precursors with Cp ligands are more difficult to adsorb on the partially decomposed precursor-on-surface. Our findings intend to offer a fundamental molecular-level understanding of the thermal stability of group 4 precursors for high-temperature ALD.

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The effects of decomposition of CpZr(NMe2)3 on atomic layer deposition for high-k ZrO2 thin films

Cited by 5 publications

References 24 publications

Ab Initio Prediction of Vapor Pressure for Diverse Atomic Layer Deposition Precursors

Ab Initio Prediction of Vapor Pressure for Diverse Atomic Layer Deposition Precursors

Atomic Layer Deposition of HfO₂ Films Using Tetrakis(1-(N,N-dimethylamino)-2-propoxy)hafnium [Hf(dmap)₄] for Advanced Gate Dielectrics Applications

Role of Cyclopentadienyl Ligands of Group 4 Precursors toward High-Temperature Atomic Layer Deposition

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The effects of decomposition of CpZr(NMe2)3 on atomic layer deposition for high-k ZrO2 thin films

Cited by 5 publications

References 24 publications

Ab Initio Prediction of Vapor Pressure for Diverse Atomic Layer Deposition Precursors

Ab Initio Prediction of Vapor Pressure for Diverse Atomic Layer Deposition Precursors

Atomic Layer Deposition of HfO2 Films Using Tetrakis(1-(N,N-dimethylamino)-2-propoxy)hafnium [Hf(dmap)4] for Advanced Gate Dielectrics Applications

Role of Cyclopentadienyl Ligands of Group 4 Precursors toward High-Temperature Atomic Layer Deposition

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Atomic Layer Deposition of HfO₂ Films Using Tetrakis(1-(N,N-dimethylamino)-2-propoxy)hafnium [Hf(dmap)₄] for Advanced Gate Dielectrics Applications