A first-principles study of the atomic layer deposition of ZnO on carboxyl functionalized carbon nanotubes: the role of water molecules

<div>HfO2 and ZrO2 are two high-k materials that are important in the down-scaling of semiconductor devices. Atomic level control of material processing is required for fabrication of thin films of these materials at nanoscale device sizes. Thermal Atomic Layer Etch (ALE) of metal oxides, in which up to one monolayer of the material can be removed, can be achieved by sequential self-limiting fluorination and ligand-exchange reactions at elevated temperatures. However, to date a detailed atomistic understanding of the mechanism of thermal ALE of these technologically important oxides is lacking. In this paper, we investigate the hydrogen fluoride pulse in the first step in the thermal ALE process of HfO2 and ZrO2 using first principles simulations. We introduce Natarajan-Elliott analysis, a thermodynamic methodology, to compare reaction models representing the self-limiting (SL) and continuous spontaneous etch (SE) processes taking place during an ALE pulse. Applying this method to the first HF pulse on HfO2 and ZrO2 we found that thermodynamic barriers impeding continuous etch are present at ALE relevant temperatures. We performed explicit HF adsorption calculations on the oxide surfaces to understand the mechanistic details of the HF pulse. A HF molecule adsorbs dissociatively on both oxides by forming metal-F and O-H bonds. HF coverages ranging from 1.0 0.3 to 17.0 0.3 HF/nm2 are investigated and a mixture of molecularly and dissociatively adsorbed HF molecules is present at higher coverages. Theoretical etch rates of -0.61 0.02 Å /cycle for HfO2 and -0.57 0.02 Å /cycle ZrO2 were calculated using maximum coverages of 7.0 0.3 and 6.5 0.3 M-F bonds/nm2 respectively (M = Hf, Zr).</div>

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Ligand Assisted Volatilization and Thermal Stability of [(t-BuN=)2MoCl2]2

10.26434/chemrxiv.9413573 ◽

2019 ◽

Author(s):

Michael Land ◽

Katherine Roberston ◽

Sean Barry

Keyword(s):

Thermal Stability ◽

Ligand Exchange ◽

Atomic Layer ◽

Exchange Reactions ◽

X Ray Crystallography ◽

Layer Deposition ◽

Neutral Ligands ◽

Solid State Structures ◽

Tga And Dsc ◽

Thermal Stability Of

Volatile molybdenum containing compounds have successfully been utilized for the atomic layer deposition of MoNx, MoO3, MoS2, and MoCxNy. Most of the reported volatile molybdenum containing compounds have been prepared via salt metathesis reactions of bis(tert-butylimido)-dichloromolybdenum(VI), with anionic nitrogen based ligands. Herein we describe the preparation of several adducts of [(t-BuN=)2MoCl2]2 (2) via ligand exchange reactions with various neutral ligands, including both mono- and bidentate ethers, amines, and phosphines, as well as an N-heterocyclic carbene (NHC). These compounds have been characterized using NMR spectroscopy, elemental analysis, and the solid-state structures have been determined using single crystal X-ray crystallography. The volatility and thermal stability of all compounds have been assessed using TGA and DSC, showing that the coordinated ligands can improve the volatility, but in many cases the gas phase species reverts to 2. This highlights a strategy for using coordinative ligands that are easily thermolyzed during evaporation and delivery yet improve the volatility of a key precursor.

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Mechanism of the HF Pulse in the Thermal Atomic Layer Etch of HfO2 and ZrO2: A First Principles Study

10.26434/chemrxiv.11310860.v1 ◽

2019 ◽

Author(s):

Rita Mullins ◽

Suresh Natarajan ◽

Simon D. Elliott ◽

Michael Nolan

Keyword(s):

First Principles ◽

Ligand Exchange ◽

Elevated Temperatures ◽

Atomic Layer ◽

Level Control ◽

Exchange Reactions ◽

Nanoscale Device ◽

High K ◽

Reaction Models ◽

High K Materials

<div>HfO2 and ZrO2 are two high-k materials that are important in the down-scaling of semiconductor devices. Atomic level control of material processing is required for fabrication of thin films of these materials at nanoscale device sizes. Thermal Atomic Layer Etch (ALE) of metal oxides, in which up to one monolayer of the material can be removed, can be achieved by sequential self-limiting fluorination and ligand-exchange reactions at elevated temperatures. However, to date a detailed atomistic understanding of the mechanism of thermal ALE of these technologically important oxides is lacking. In this paper, we investigate the hydrogen fluoride pulse in the first step in the thermal ALE process of HfO2 and ZrO2 using first principles simulations. We introduce Natarajan-Elliott analysis, a thermodynamic methodology, to compare reaction models representing the self-limiting (SL) and continuous spontaneous etch (SE) processes taking place during an ALE pulse. Applying this method to the first HF pulse on HfO2 and ZrO2 we found that thermodynamic barriers impeding continuous etch are present at ALE relevant temperatures. We performed explicit HF adsorption calculations on the oxide surfaces to understand the mechanistic details of the HF pulse. A HF molecule adsorbs dissociatively on both oxides by forming metal-F and O-H bonds. HF coverages ranging from 1.0 0.3 to 17.0 0.3 HF/nm2 are investigated and a mixture of molecularly and dissociatively adsorbed HF molecules is present at higher coverages. Theoretical etch rates of -0.61 0.02 Å /cycle for HfO2 and -0.57 0.02 Å /cycle ZrO2 were calculated using maximum coverages of 7.0 0.3 and 6.5 0.3 M-F bonds/nm2 respectively (M = Hf, Zr).</div>

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Ligand Assisted Volatilization and Thermal Stability of [(t-BuN=)2MoCl2]2

10.26434/chemrxiv.9413573.v1 ◽

2019 ◽

Author(s):

Michael Land ◽

Katherine Roberston ◽

Sean Barry

Keyword(s):

Thermal Stability ◽

Ligand Exchange ◽

Atomic Layer ◽

Exchange Reactions ◽

X Ray Crystallography ◽

Layer Deposition ◽

Neutral Ligands ◽

Solid State Structures ◽

Tga And Dsc ◽

Thermal Stability Of

Volatile molybdenum containing compounds have successfully been utilized for the atomic layer deposition of MoNx, MoO3, MoS2, and MoCxNy. Most of the reported volatile molybdenum containing compounds have been prepared via salt metathesis reactions of bis(tert-butylimido)-dichloromolybdenum(VI), with anionic nitrogen based ligands. Herein we describe the preparation of several adducts of [(t-BuN=)2MoCl2]2 (2) via ligand exchange reactions with various neutral ligands, including both mono- and bidentate ethers, amines, and phosphines, as well as an N-heterocyclic carbene (NHC). These compounds have been characterized using NMR spectroscopy, elemental analysis, and the solid-state structures have been determined using single crystal X-ray crystallography. The volatility and thermal stability of all compounds have been assessed using TGA and DSC, showing that the coordinated ligands can improve the volatility, but in many cases the gas phase species reverts to 2. This highlights a strategy for using coordinative ligands that are easily thermolyzed during evaporation and delivery yet improve the volatility of a key precursor.

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First-Principles Study on Electron-Induced Excitations of Atomic Layer Deposition Precursors: Inelastic Electron Wave Packet Scattering with Cobalt Tricarbonyl Nitrosyl Co(CO)3NO Using Time-Dependent Density Functional Theory

The Journal of Physical Chemistry A ◽

10.1021/acs.jpca.0c11309 ◽

2021 ◽

Author(s):

Xiaolong Yao ◽

Yeonghun Lee ◽

Davide Ceresoli ◽

Kyeongjae Cho

Keyword(s):

First Principles ◽

Density Functional ◽

Atomic Layer ◽

Time Dependent ◽

Inelastic Electron ◽

Electron Wave ◽

Functional Theory ◽

Electron Wave Packet ◽

Layer Deposition ◽

Dependent Density

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Atomic layer deposition of ternary ruthenates by combining metalorganic precursors with RuO4 as the co-reactant

Dalton Transactions ◽

10.1039/d1dt03543f ◽

2021 ◽

Author(s):

Matthias Marcus Minjauw ◽

Ji-Yu Feng ◽

Timo Sajavaara ◽

Christophe Detavernier ◽

Jolien Dendooven

Keyword(s):

Atomic Layer Deposition ◽

Atomic Layer ◽

Ruthenium Tetroxide ◽

Layer Deposition

In this work, the use of ruthenium tetroxide (RuO4) as a co-reactant for atomic layer deposition (ALD) is reported. The role of RuO4 as a co-reactant is twofold: it acts...

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