scholarly journals First principles study of the atomic layer deposition of alumina by TMA–H2O-process

2015 ◽  
Vol 17 (26) ◽  
pp. 17322-17334 ◽  
Author(s):  
Timo Weckman ◽  
Kari Laasonen
Keyword(s):  
Atomic Layer Deposition ◽  
First Principles ◽  
Reaction Mechanisms ◽  
Density Functional ◽  
Atomic Layer ◽  
Functional Study ◽  
Density Functional Study ◽  
First Principles Study ◽  
Layer Deposition

A comprehensive density functional study on the reaction mechanisms during the atomic layer deposition of alumina via trimethylaluminium–waterprocess.

scholarly journals First-principles study of the surface reactions of aminosilane precursors over WO3(001) during atomic layer deposition of SiO2

RSC Advances ◽  
2020 ◽  
Vol 10 (28) ◽  
pp. 16584-16592
Author(s):  
Kyungtae Lee ◽  
Youngseon Shim
Keyword(s):  
Atomic Layer Deposition ◽  
First Principles ◽  
Surface Reactions ◽  
Atomic Layer ◽  
Reaction Pathways ◽  
Energy Diagram ◽  
First Principles Study ◽  
Layer Deposition

Energy diagram of reaction pathways for decomposition of different aminosilane precursors on a WO3 (001) surface.

scholarly journals Dissociation reaction of B2H6 on TiN surfaces during atomic layer deposition: first-principles study

RSC Advances ◽  
2017 ◽  
Vol 7 (88) ◽  
pp. 55750-55755 ◽  
Author(s):  
Hwanyeol Park ◽  
Sungwoo Lee ◽  
Ho Jun Kim ◽  
Euijoon Yoon ◽  
Gun-Do Lee
Keyword(s):  
Atomic Layer Deposition ◽  
First Principles ◽  
Atomic Layer ◽  
Fabrication Process ◽  
Device Performance ◽  
Memory Devices ◽  
Dissociation Reaction ◽  
First Principles Study ◽  
Layer Deposition

In the fabrication process of memory devices, a void-free tungsten (W) gate process with good conformability is very important for improving the conductivity of the W gate, leading to enhancement of device performance.

scholarly journals First Principles Mechanistic Study of Self-Limiting Oxidative Adsorption of Remote Oxygen Plasma During the Atomic Layer Deposition of Alumina

2018 ◽  
Author(s):  
Glen N. Fomengia ◽  
Michael Nolan ◽  
Simon D. Elliott
Keyword(s):  
Atomic Layer Deposition ◽  
First Principles ◽  
Density Functional ◽  
Atomic Layer ◽  
Molecular Water ◽  
Mechanistic Study ◽  
Hydroxyl Groups ◽  
Layer Deposition ◽  
Surface Intermediates ◽  
By Products

Plasma-enhanced atomic layer deposition (ALD) of metal oxides is a rapidly gaining interest especially in the electronics industry because of its numerous advantages over the thermal process. However, the underlying reaction mechanism is not sufficiently understood, particularly regarding saturation of the reaction and densification of the film. In this work, we employ first principles density functional theory (DFT) to determine the predominant reaction pathways, surface intermediates and by-products formed when constituents of O<sub>2</sub>-plasma or O<sub>3</sub> adsorb onto a methylated surface typical of TMA-based alumina ALD. The main outcomes are that a wide variety of barrierless and highly exothermic reactions can take place. This leads to the spontaneous production of various by-products with low desorption energies and also of surface intermediates from the incomplete combustion of –CH<sub>3</sub> ligands. Surface hydroxyl groups are the most frequently observed intermediate and are formed as a consequence of the conservation of atoms and charge when methyl ligands are initially oxidized (rather than from subsequent re-adsorption of molecular water). Anionic intermediates such as formates are also commonly observed at the surface in the simulations. Formaldehyde, CH<sub>2</sub>O, is the most frequently observed gaseous by-product. Desorption of this by-product leads to saturation of the redox reaction at the level of two singlet oxygen atoms per CH<sub>3</sub> group, where the oxidation state of C is zero, rather than further reaction with oxygen to higher oxidation states. We conclude that the self-limiting chemistry that defines ALD comes about in this case through the desorption by-products with partially-oxidised carbon. The simulations also show that densification occurs when ligands are removed or oxidised to intermediates, indicating that there may be an inverse relationship between Al/O coordination numbers in the final film and the concentration of chemically-bound ligands or intermediate fragments covering the surface during each ALD pulse. Therefore reactions that generate a bare surface Al will produce denser films in metal oxide ALD.

scholarly journals Overall reaction mechanism for a full atomic layer deposition cycle of W films on TiN surfaces: first-principles study

RSC Advances ◽  
2018 ◽  
Vol 8 (68) ◽  
pp. 39039-39046 ◽  
Author(s):  
Hwanyeol Park ◽  
Sungwoo Lee ◽  
Ho Jun Kim ◽  
Daekwang Woo ◽  
Jong Myeong Lee ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Atomic Layer Deposition ◽  
First Principles ◽  
Dft Calculation ◽  
Atomic Layer ◽  
Deposition Cycle ◽  
Atomic Layer Deposition Cycle ◽  
First Principles Study ◽  
Layer Deposition ◽  
Dissociative Reactions

We investigated the overall ALD reaction mechanism for W deposition on TiN surfaces based on DFT calculation as well as the detailed dissociative reactions of WF6.

Tuning electronic structure of BaTiO3 for enhanced photocatalytic performance using cation-anion codoping: A first-principles study

2021 ◽  
Author(s):  
Yumeng Fo ◽  
Yanxia Ma ◽  
Hao Dong ◽  
Xin Zhou
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Photocatalytic Performance ◽  
Functional Study ◽  
Density Functional Study ◽  
First Principles Study ◽  
Hybrid Density Functional

Codoping with cation and anion is found to be an effective approach to tailor the electronic structures of semiconductor-based photocatalysts. In this work, a systematic hybrid density functional study has...

First-Principles Study of a Full Cycle of Atomic Layer Deposition of SiO2Thin Films with Di(sec-butylamino)silane and Ozone

2013 ◽  
pp. 130911145338002 ◽  
Author(s):  
Liang Huang ◽  
Bo Han ◽  
Bing Han ◽  
Agnes Derecskei-Kovacs ◽  
Manchao Xiao ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
First Principles ◽  
Atomic Layer ◽  
First Principles Study ◽  
Layer Deposition

scholarly journals First Principles Mechanistic Study of Self-Limiting Oxidative Adsorption of Remote Oxygen Plasma During the Atomic Layer Deposition of Alumina

2018 ◽  
Author(s):  
Glen N. Fomengia ◽  
Michael Nolan ◽  
Simon D. Elliott
Keyword(s):  
Atomic Layer Deposition ◽  
First Principles ◽  
Density Functional ◽  
Atomic Layer ◽  
Molecular Water ◽  
Mechanistic Study ◽  
Hydroxyl Groups ◽  
Layer Deposition ◽  
Surface Intermediates ◽  
By Products

Plasma-enhanced atomic layer deposition (ALD) of metal oxides is a rapidly gaining interest especially in the electronics industry because of its numerous advantages over the thermal process. However, the underlying reaction mechanism is not sufficiently understood, particularly regarding saturation of the reaction and densification of the film. In this work, we employ first principles density functional theory (DFT) to determine the predominant reaction pathways, surface intermediates and by-products formed when constituents of O<sub>2</sub>-plasma or O<sub>3</sub> adsorb onto a methylated surface typical of TMA-based alumina ALD. The main outcomes are that a wide variety of barrierless and highly exothermic reactions can take place. This leads to the spontaneous production of various by-products with low desorption energies and also of surface intermediates from the incomplete combustion of –CH<sub>3</sub> ligands. Surface hydroxyl groups are the most frequently observed intermediate and are formed as a consequence of the conservation of atoms and charge when methyl ligands are initially oxidized (rather than from subsequent re-adsorption of molecular water). Anionic intermediates such as formates are also commonly observed at the surface in the simulations. Formaldehyde, CH<sub>2</sub>O, is the most frequently observed gaseous by-product. Desorption of this by-product leads to saturation of the redox reaction at the level of two singlet oxygen atoms per CH<sub>3</sub> group, where the oxidation state of C is zero, rather than further reaction with oxygen to higher oxidation states. We conclude that the self-limiting chemistry that defines ALD comes about in this case through the desorption by-products with partially-oxidised carbon. The simulations also show that densification occurs when ligands are removed or oxidised to intermediates, indicating that there may be an inverse relationship between Al/O coordination numbers in the final film and the concentration of chemically-bound ligands or intermediate fragments covering the surface during each ALD pulse. Therefore reactions that generate a bare surface Al will produce denser films in metal oxide ALD.

scholarly journals First-Principles Studies of Nucleation of Atomic-Layered Molybdenum Disulfide by Atomic Layer Deposition

2021 ◽  
Author(s):  
Matthew Lawson
Keyword(s):  
Atomic Layer Deposition ◽  
Molybdenum Disulfide ◽  
First Principles ◽  
Density Functional ◽  
Atomic Layer ◽  
Atomic Scale ◽  
Half Cycle ◽  
Scale Thickness ◽  
Layer Deposition ◽  
Nucleation Mechanisms

This dissertation implements first-principles calculations to understand the nucleation mechanisms for atomic layer deposition (ALD) of molybdenum disulfide (MoS2) using MoF6 and H2S precursors. ALD is a self-limiting process that can deposit a range of materials at the nanoscale, while maintaining chemical stoichiometry, atomic scale thickness control, and can conform to high-aspect ratio substrate designs. ALD is extremely sensitive to surface chemistry and morphology; therefore, it is critical to understand how these factors control deposition. Density functional theory (DFT) was used to understand what factors can control the nucleation for ALD of MoS2 using MoF6 and H2S. Surface hydroxyls on oxide substrates help facilitate the formation of ionic MFx (M = metal, x = 1, 2, 3) species, which thermodynamically drive the first-half cycle of ALD. DFT calculations were supported by experimental measurements to validate computational predictions. DFT and experiment both confirmed that there are different types of nucleation mechanisms during ALD of MoS2. The types of mechanisms depend on which precursor is introduced, and highlights the complexities during nucleation of MoS2 during ALD.

Initial Surface Reactions Mechanisms of Atomic Layer Deposition TiO2 on H/Si(100)-2×1 Surface

2013 ◽  
Vol 750-752 ◽  
pp. 1052-1056 ◽  
Author(s):  
Guang Fen Zhou ◽  
Jie Ren ◽  
Shao Wen Zhang
Keyword(s):  
Density Functional Theory ◽  
Atomic Layer Deposition ◽  
Adsorption Energy ◽  
Reaction Mechanisms ◽  
Density Functional ◽  
Surface Reaction ◽  
Atomic Layer ◽  
Initial Surface ◽  
Functional Theory ◽  
Layer Deposition

The initial surface reaction mechanisms of atomic layer deposition TiO2on H/Si (100 )-2×1 surface using Ti (OCH3)4and H2O as precursors are investigated by density functional theory. The ALD process is divided into two half-reactions, i.e., Ti (OCH3)4and H2O half-reactions. The adsorption energy of Ti (OCH3)4on H/Si (100)2×1 surface is only-2.4 kJ/mol. The overall reaction of Ti (OCH3)4is exothermic, which indicates that Ti (OCH3)4half-reactions are favorable on thermodynamic. Howerver, H2O half-reactions are endothermic and thermodynamically unfavorable.

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