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A model-based methodology for the analysis and design of atomic layer deposition processes-Part I: Mechanistic modelling of continuous flow reactors

Holmqvist, Anders LU ; Torndahl, Tobias and Stenström, Stig LU (2012) In Chemical Engineering Science 81. p.260-272
Abstract
This paper presents the development of an experimentally validated model that mechanistically comprehends the complex interaction between the gas-phase fluid dynamics, the mass transport of individual species, and the heterogeneous gas-surface reaction mechanism in a continuous cross-flow atomic layer deposition (ALD) reactor. The developed ALD gas-surface reaction mechanism, purely based on consecutive and parallel elementary Eley-Rideal reaction steps, was incorporated into the computational fluid dynamic representation of the equipment-scale. Thereby, the model mechanistically relates local gas-phase conditions in the vicinity of the substrate surface to the transient production and consumption of the fractional surface coverage of... (More)
This paper presents the development of an experimentally validated model that mechanistically comprehends the complex interaction between the gas-phase fluid dynamics, the mass transport of individual species, and the heterogeneous gas-surface reaction mechanism in a continuous cross-flow atomic layer deposition (ALD) reactor. The developed ALD gas-surface reaction mechanism, purely based on consecutive and parallel elementary Eley-Rideal reaction steps, was incorporated into the computational fluid dynamic representation of the equipment-scale. Thereby, the model mechanistically relates local gas-phase conditions in the vicinity of the substrate surface to the transient production and consumption of the fractional surface coverage of chemisorbed species, ultimately underlying epitaxial film growth. The model is oriented towards optimization and control and enables identification of substrate film thickness uniformity sensitivities to process operating parameters, reactor system design and gas flow distribution. For the experimental validation of the derived mathematical model, a detailed experimental investigation with the focus on the impact of process operating parameters on the spatial evolution of ZnO film thickness profile was performed. The controlled deposition of ZnO from Zn(C2H5)(2) and H2O was carried out in the continuous cross-flow ALD reactor system F-120 by ASM Microchemistry Ltd. and ex situ film thickness measurements at a discrete set of sampling positions on the substrate were performed using X-ray reflectivity and X-ray fluorescence analysis. The experimental results reported here, underscore the importance of substrate-scale uniformity measurements in developing mechanistic ALD process models with high predictability of the dynamic evolution of the spatially dependent film thickness profile. The experimental validation and extensive mechanistic analysis of the ALD reactor model are presented in the second article of this series (Holmqvist et al., in press). (C) 2012 Elsevier Ltd. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Atomic layer deposition, Ex situ film characterization, Mathematical, modelling, Computational fluid dynamics, Transport processes, Reaction, engineering
in
Chemical Engineering Science
volume
81
pages
260 - 272
publisher
Elsevier
external identifiers
  • wos:000307885000025
  • scopus:84864506085
ISSN
0009-2509
DOI
10.1016/j.ces.2012.07.015
language
English
LU publication?
yes
id
d7a8cb2f-afec-4f18-aad6-709ee12353b9 (old id 3189662)
date added to LUP
2012-12-04 14:46:54
date last changed
2017-08-20 04:05:48
@article{d7a8cb2f-afec-4f18-aad6-709ee12353b9,
  abstract     = {This paper presents the development of an experimentally validated model that mechanistically comprehends the complex interaction between the gas-phase fluid dynamics, the mass transport of individual species, and the heterogeneous gas-surface reaction mechanism in a continuous cross-flow atomic layer deposition (ALD) reactor. The developed ALD gas-surface reaction mechanism, purely based on consecutive and parallel elementary Eley-Rideal reaction steps, was incorporated into the computational fluid dynamic representation of the equipment-scale. Thereby, the model mechanistically relates local gas-phase conditions in the vicinity of the substrate surface to the transient production and consumption of the fractional surface coverage of chemisorbed species, ultimately underlying epitaxial film growth. The model is oriented towards optimization and control and enables identification of substrate film thickness uniformity sensitivities to process operating parameters, reactor system design and gas flow distribution. For the experimental validation of the derived mathematical model, a detailed experimental investigation with the focus on the impact of process operating parameters on the spatial evolution of ZnO film thickness profile was performed. The controlled deposition of ZnO from Zn(C2H5)(2) and H2O was carried out in the continuous cross-flow ALD reactor system F-120 by ASM Microchemistry Ltd. and ex situ film thickness measurements at a discrete set of sampling positions on the substrate were performed using X-ray reflectivity and X-ray fluorescence analysis. The experimental results reported here, underscore the importance of substrate-scale uniformity measurements in developing mechanistic ALD process models with high predictability of the dynamic evolution of the spatially dependent film thickness profile. The experimental validation and extensive mechanistic analysis of the ALD reactor model are presented in the second article of this series (Holmqvist et al., in press). (C) 2012 Elsevier Ltd. All rights reserved.},
  author       = {Holmqvist, Anders and Torndahl, Tobias and Stenström, Stig},
  issn         = {0009-2509},
  keyword      = {Atomic layer deposition,Ex situ film characterization,Mathematical,modelling,Computational fluid dynamics,Transport processes,Reaction,engineering},
  language     = {eng},
  pages        = {260--272},
  publisher    = {Elsevier},
  series       = {Chemical Engineering Science},
  title        = {A model-based methodology for the analysis and design of atomic layer deposition processes-Part I: Mechanistic modelling of continuous flow reactors},
  url          = {http://dx.doi.org/10.1016/j.ces.2012.07.015},
  volume       = {81},
  year         = {2012},
}