Preparation of Tetramethylzirconium, Zr(CH<sub>3</sub>)<sub>4</sub>

Berthold, H. J.; Groh, G.

doi:10.1002/anie.196605162

Cited by 18 publications

(20 citation statements)

References 2 publications

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“…7 These results were explained by the instability of Zr(CH 3 ) 4 at high temperature. 7,36 In contrast, DMAC can transfer Cl ligands and form ZrCl 4 or ZrCl x F 4−x mixed halogen species. ZrCl 4 is stable and volatile at 250 °C.…”

Section: Methodsmentioning

confidence: 99%

Thermal Atomic Layer Etching of Al₂O₃, HfO₂, and ZrO₂ Using Sequential Hydrogen Fluoride and Dimethylaluminum Chloride Exposures

Lee

George

2019

J. Phys. Chem. C

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Atomic layer etching (ALE) of Al 2 O 3 , HfO 2 , and ZrO 2 was accomplished using sequential exposures with hydrogen fluoride (HF) as the fluorination reagent and dimethylaluminum chloride (DMAC, AlCl(CH 3 ) 2 ) as the metal reactant for ligand exchange. DMAC could provide either CH 3 or Cl ligands for the ligand-exchange reaction. The presence of the Cl ligand on DMAC led to efficient HfO 2 and ZrO 2 etching attributed to the formation of stable and volatile chloride species. In situ quartz crystal microbalance (QCM) measurement observed mass changes during Al 2 O 3 , HfO 2 , and ZrO 2 ALE reactions at 200−300 °C. Al 2 O 3 , HfO 2 , and ZrO 2 were etched linearly versus number of HF and DMAC sequential exposures. The QCM analysis confirmed that the HF and DMAC reactions were self-limiting versus reactant exposure. The QCM studies observed mass changes per cycle (MCPC) of −12.2 ng/(cm 2 cycle), −94.1 ng/(cm 2 cycle), and −75.6 ng/(cm 2 cycle) for Al 2 O 3 , HfO 2 , and ZrO 2 ALE, respectively, at 250 °C. These MCPC correspond to Al 2 O 3 , HfO 2 , and ZrO 2 etch rates of 0.39 Å/cycle, 0.98 Å/cycle, and 1.33 Å/cycle, respectively. In comparison, the AlF 3 , HfF 4 , and ZrF 4 surface layers were estimated to have thicknesses of 3.0 Å, 3.3 Å, and 4.4 Å on Al 2 O 3 , HfO 2 , and ZrO 2 , respectively. The magnitudes of these fluoride thicknesses have the same ordering as the etch rates for Al 2 O 3 , HfO 2 , and ZrO 2 ALE, respectively. X-ray reflectivity (XRR) and spectroscopic ellipsometry measurements verified the etch rates for Al 2 O 3 ALE. XRR analysis also confirmed smoothening of the etched Al 2 O 3 film. The etch rates for Al 2 O 3 , HfO 2 , and ZrO 2 ALE increased with temperature from 200 to 300 °C. A comparison of Al 2 O 3 , HfO 2 , and ZrO 2 ALE using either HF and DMAC or HF and trimethylaluminum (TMA, Al(CH 3 ) 3 ) revealed that higher etch rates were observed for DMAC for all three materials. Crosssectional transmission electron microscopy (TEM) studies also revealed that Al 2 O 3 ALE on masked Al 2 O 3 substrates was isotropic and selective in the presence of SiN and SiO 2 . Because of the ability of DMAC to provide either CH 3 or Cl ligands during the ligand-exchange reaction, DMAC should be a very useful metal reactant for the thermal ALE of various materials.

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Section: Methodsmentioning

confidence: 99%

Thermal Atomic Layer Etching of Al₂O₃, HfO₂, and ZrO₂ Using Sequential Hydrogen Fluoride and Dimethylaluminum Chloride Exposures

Lee

George

2019

J. Phys. Chem. C

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“…The metal precursor Al(CH 3 ) 3 could remove AlF 3 during Al 2 O 3 ALE because Al(CH 3 ) 3 or AlF(CH 3 ) 2 are stable and volatile metal reaction products . In contrast, Al(CH 3 ) 3 is not expected to remove ZrF 4 to perform ZrO 2 ALE because Zr(CH 3 ) 4 or ZrF(CH 3 ) 3 are not stable metal reaction products …”

Section: Pathways To Selectivitymentioning

confidence: 99%

“…14 In contrast, Al(CH 3 ) 3 is not expected to remove ZrF 4 to perform ZrO 2 ALE because Zr(CH 3 ) 4 or ZrF(CH 3 ) 3 are not stable metal reaction products. 15 Recent experiments have revealed selectivity in thermal ALE. 16 Figure 4 shows results for ALE using sequential HF and TMA exposures on TiN, SiO 2 , Si 3 N 4 , Al 2 O 3 , HfO 2 , and ZrO 2 thin films at 300 °C.…”

Section: Pathways To Selectivitymentioning

confidence: 99%

Prospects for Thermal Atomic Layer Etching Using Sequential, Self-Limiting Fluorination and Ligand-Exchange Reactions

2016

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Thermal atomic layer etching (ALE) of Al2O3 and HfO2 using sequential, self-limiting fluorination and ligand-exchange reactions was recently demonstrated using HF and tin acetylacetonate (Sn(acac)2) as the reactants. This new thermal pathway for ALE represents the reverse of atomic layer deposition (ALD) and should lead to isotropic etching. Atomic layer deposition and ALE can together define the atomic layer growth and removal steps required for advanced semiconductor fabrication. The thermal ALE of many materials should be possible using fluorination and ligand-exchange reactions. The chemical details of ligand-exchange can lead to selective ALE between various materials. Thermal ALE could produce conformal etching in high-aspect-ratio structures. Thermal ALE could also yield ultrasmooth thin films based on deposit/etch-back methods. Enhancement of ALE rates and possible anisotropic ALE could be achieved using radicals or ions together with thermal ALE.

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“…The synthesis of the supported pre-catalyst required the first preparation of pure (THF) 2 Zr(Me) 4 (Me= Methyl; THF = tetrahydrofuran). Zr(Me) 4 was first reported in 1966 by Berthold and Groh, 16 who investigated its decomposition and claimed to have synthesized an ethereal bound Zr(CH 3 ) 4 , although supporting NMR data were lacking. 16 In 1989, Morse et al reported the alkylation of MCl 4 (dippe) (M=Zr or Hf) by MgMe 2 to form M(Me) 4 (dippe).…”

Section: The Metal Complex (Zr(ch 3 ) 4 (Thf) 2 ) Has Been Fully Syntmentioning

confidence: 99%

“…Zr(Me) 4 was first reported in 1966 by Berthold and Groh, 16 who investigated its decomposition and claimed to have synthesized an ethereal bound Zr(CH 3 ) 4 , although supporting NMR data were lacking. 16 In 1989, Morse et al reported the alkylation of MCl 4 (dippe) (M=Zr or Hf) by MgMe 2 to form M(Me) 4 (dippe). 17 In 2012 Nishida et al 18 prepared an ethereal solution of Zr(CH 3 ) 4 in-situ and used it for the ketone to alcohol reduction.…”

Section: The Metal Complex (Zr(ch 3 ) 4 (Thf) 2 ) Has Been Fully Syntmentioning

confidence: 99%

Docking of tetra-methyl zirconium to the surface of silica: a well-defined pre-catalyst for conversion of CO₂ to cyclic carbonates

et al. 2020

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Preparation of Tetramethylzirconium, Zr(CH₃)₄

Cited by 18 publications

References 2 publications

Thermal Atomic Layer Etching of Al₂O₃, HfO₂, and ZrO₂ Using Sequential Hydrogen Fluoride and Dimethylaluminum Chloride Exposures

Thermal Atomic Layer Etching of Al₂O₃, HfO₂, and ZrO₂ Using Sequential Hydrogen Fluoride and Dimethylaluminum Chloride Exposures

Prospects for Thermal Atomic Layer Etching Using Sequential, Self-Limiting Fluorination and Ligand-Exchange Reactions

Docking of tetra-methyl zirconium to the surface of silica: a well-defined pre-catalyst for conversion of CO₂ to cyclic carbonates

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Preparation of Tetramethylzirconium, Zr(CH3)4

Cited by 18 publications

References 2 publications

Thermal Atomic Layer Etching of Al2O3, HfO2, and ZrO2 Using Sequential Hydrogen Fluoride and Dimethylaluminum Chloride Exposures

Thermal Atomic Layer Etching of Al2O3, HfO2, and ZrO2 Using Sequential Hydrogen Fluoride and Dimethylaluminum Chloride Exposures

Prospects for Thermal Atomic Layer Etching Using Sequential, Self-Limiting Fluorination and Ligand-Exchange Reactions

Docking of tetra-methyl zirconium to the surface of silica: a well-defined pre-catalyst for conversion of CO2 to cyclic carbonates

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Preparation of Tetramethylzirconium, Zr(CH₃)₄

Thermal Atomic Layer Etching of Al₂O₃, HfO₂, and ZrO₂ Using Sequential Hydrogen Fluoride and Dimethylaluminum Chloride Exposures

Thermal Atomic Layer Etching of Al₂O₃, HfO₂, and ZrO₂ Using Sequential Hydrogen Fluoride and Dimethylaluminum Chloride Exposures

Docking of tetra-methyl zirconium to the surface of silica: a well-defined pre-catalyst for conversion of CO₂ to cyclic carbonates