Abstract
Atomic layer deposition (ALD) is a technique for depositing thin films of materials with a precise thickness control and uniformity using the self-limitation of the underlying reactions. Usually, it is difficult to predict the result of the ALD process for given external parameters, e.g., the precursor exposure time or the size of the precursor molecules. Therefore, a deeper insight into ALD by modeling the process is needed to improve process control and to achieve more economical coatings. In this paper, a detailed, microscopic approach based on the model developed by Yanguas-Gil and Elam is presented and additionally compared with the experiment. Precursor diffusion and second-order reaction kinetics are combined to identify the influence of the porous substrate's microstructural parameters and the influence of precursor properties on the coating. The thickness of the deposited film is calculated for different depths inside the porous structure in relation to the precursor exposure time, the precursor vapor pressure, and other parameters. Good agreement with experimental results was obtained for ALD zirconiumdioxide (ZrO2) films using the precursors tetrakis(ethylmethylamido)zirconium and O2. The derivation can be adjusted to describe other features of ALD processes, e.g., precursor and reactive site losses, different growth modes, pore size reduction, and surface diffusion.
Highlights
Atomic layer deposition (ALD) is a vacuum-based technique to deposit thin films of certain materials with a precise thickness control in the order of less than one nanometer.1–7 ALD starts with two gaseous chemicals known as precursors
Atomic layer deposition (ALD) is a technique for depositing thin films of materials with a precise thickness control and uniformity using the self-limitation of the underlying reactions
It is difficult to predict the result of the ALD process for given external parameters, e.g., the precursor exposure time or the size of the precursor molecules
Summary
Atomic layer deposition (ALD) is a vacuum-based technique to deposit thin films of certain materials with a precise thickness control in the order of less than one nanometer. ALD starts with two gaseous chemicals known as precursors. In consequence of steric hindrance effects or a low density of reactive sites, even less than one monolayer is usually deposited In this way, inner surfaces of porous structures can be coated with a low risk of blocking pores. In order to overcome these shortcomings, a more detailed, microscopic derivation, based on second-order reaction kinetics, and an experimental comparison with a coated porous substrate is presented in this work. This detailed derivation allows a flexible application of the model to various experimental cases. In order to verify the model, a porous substrate of an anode-supported solid oxide fuel cell (SOFC) was coated and the measured thicknesses of the deposited layer were compared to the predicted coating profile. The study of the influence of ALD coatings on the oxidation tolerance will be presented in another paper
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
