Density Functional Theory (DFT)-enhanced computational fluid dynamics modeling of substrate movement and chemical deposition process in spatial atomic layer deposition

Pan, Dongqing

doi:10.1016/j.ces.2021.116447

Cited by 12 publications

(6 citation statements)

References 42 publications

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“…We note that while the geometric dimensions of the pinholes on the depositor are fixed, the spatial variations in gas pressure, composition, and velocity will depend on the detailed fluid mechanics occurring within the process region. [26,[38][39][40][41][42] These process region metrics will be directly influenced by process variables including gas flow rates, exhaust pressure, gap size, alignment, and relative motion. Previous close-proximity systems have demonstrated control over the gas flow rates and exhaust pressures, [10,17,19,22,25,26,43] but few have implemented experimental, closed-loop control over the geometric parameters (e.g., gap size and alignment changes during the deposition process), which motivated the development of the mechatronic AP-SALD system described in this study.…”

Section: Process Regionmentioning

confidence: 99%

Mechatronic Spatial Atomic Layer Deposition for Closed‐Loop and Customizable Process Control

Penley,

Cho,

Brooks

et al. 2024

Adv Materials Technologies

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A customized atmospheric‐pressure spatial atomic layer deposition (AP‐SALD) system is designed and implemented, which enables mechatronic control of key process parameters, including gap size and parallel alignment. A showerhead depositor delivers precursors to the substrate while linear actuators and capacitance probe sensors actively maintain gap size and parallel alignment through multiple‐axis tilt and closed‐loop feedback control. Digital control of geometric process variables with active monitoring is facilitated with a custom software control package and user interface. AP‐SALD of TiO2 is performed to validate self‐limiting deposition with the system. A novel multi‐axis printing methodology is introduced using x‐y position control to define a customized motion path, which enables an improvement in the thickness uniformity by reducing variations from 8% to 2%. In the future, this mechatronic system will enable experimental tuning of parameters that can inform multi‐physics modeling to gain a deeper understanding of AP‐SALD process tolerances, enabling new pathways for non‐traditional SALD processing that can push the technology towards large‐scale manufacturing.

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Section: Process Regionmentioning

confidence: 99%

Mechatronic Spatial Atomic Layer Deposition for Closed‐Loop and Customizable Process Control

Penley,

Cho,

Brooks

et al. 2024

Adv Materials Technologies

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“…Theoretical models, developed at various scales, include atomic-scale models that simulate the film growth process and study fluid dynamics within the system. At the atomic scale, models based on density functional theory (DFT) have been used to simulate and elucidate the chemical mechanisms occurring on the surface [14][15][16][17][18]. These models are instrumental in investigating the impact of ALD process parameters on aspects like film growth, thickness, and growth per cycle (GPC).…”

Section: Introductionmentioning

confidence: 99%

“…A few models that leverage fluid dynamics are used to simulate the ALD process in a threedimensional context [19][20][21]. These fluid dynamics models, or those involving transport phenomena, can become computationally and mathematically complex depending on the system geometry, requiring increased computational capacity [17,20,22,23].…”

Section: Introductionmentioning

confidence: 99%

Exploring TMA and H2O Flow Rate Effects on Al2O3 Thin Film Deposition by Thermal ALD: Insights from Zero-Dimensional Modeling

Karnopp,

Neto,

Vieira

et al. 2024

Coatings

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This study investigates the impact of vapour-phase precursor flow rates—specifically those of trimethylaluminum (TMA) and deionized water (H2O)—on the deposition of aluminum oxide (Al2O3) thin films through atomic layer deposition (ALD). It explores how these flow rates influence film growth kinetics and surface reactions, which are critical components of the ALD process. The research combines experimental techniques with a zero-dimensional theoretical model, designed specifically to simulate the deposition dynamics. This model integrates factors such as surface reactions and gas partial pressures within the ALD chamber. Experimentally, Al2O3 films were deposited at varied TMA and H2O flow rates, with system conductance guiding these rates across different temperature settings. Film properties were rigorously assessed using optical reflectance methods and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The experimental findings revealed a pronounced correlation between precursor flow rates and film growth. Specifically, at 150 °C, film thickness reached saturation at a TMA flow rate of 60 sccm, while at 200 °C, thickness peaked and then declined with increasing TMA flow above this rate. Notably, higher temperatures generally resulted in thinner films due to increased desorption rates, whereas higher water flow rates consistently produced thicker films, emphasizing the critical role of water vapour in facilitating surface reactions. This integrative approach not only deepens the understanding of deposition mechanics, particularly highlighting how variations in precursor flow rates distinctly affect the process, but also significantly advances operational parameters for ALD. These insights are invaluable for enhancing the application of ALD technologies across diverse sectors, including microelectronics, photovoltaics, and biomedical coatings, effectively bridging the gap between theoretical predictions and empirical results.

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“…26,28 On this topic, Pan used density functional theory combined with computational fluid dynamics to simulate the flow and mass transfer in SALD and found that although the substrate movement in relation to the deposition head affects the gas flow, it does not significantly disturb the separation of precursors, even at high velocities (1.5 m/s). 33 Finally, using a dynamic mesh method, Cong and colleagues showed that increasing the distance between gas injectors could be more effective at preventing precursor intermixing than increasing the flow rate of the separation gas, highlighting the important role of the head design in the deposition performance. 28 Although the above contributions provide qualitative information on the influence of some parameters of SALD systems over the film growth regime, the existing literature is still insufficient to predict whether film growth will occur by ALD or CVD when using a specific set of conditions.…”

Section: Introductionmentioning

confidence: 99%

“…The application of a slight vacuum at the exhausts, which makes them more efficient at purging the precursors, is also known to decrease precursor intermixing, , although some deposition head designs can operate well without vacuum at the exhaust . Moreover, several studies suggest that moving the head slowly relative to the substrate generates high-quality films by not dragging precursors from one region to the other during movement. , On this topic, Pan used density functional theory combined with computational fluid dynamics to simulate the flow and mass transfer in SALD and found that although the substrate movement in relation to the deposition head affects the gas flow, it does not significantly disturb the separation of precursors, even at high velocities (1.5 m/s) . Finally, using a dynamic mesh method, Cong and colleagues showed that increasing the distance between gas injectors could be more effective at preventing precursor intermixing than increasing the flow rate of the separation gas, highlighting the important role of the head design in the deposition performance …”

Section: Introductionmentioning

confidence: 99%

Can We Rationally Design and Operate Spatial Atomic Layer Deposition Systems for Steering the Growth Regime of Thin Films?

et al. 2023

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Fine control over the growth of materials is required to precisely tailor their properties. Spatial atomic layer deposition (SALD) is a thin-film deposition technique that has recently attracted attention because it allows producing thin films with a precise number of deposited layers, while being vacuum-free and much faster than conventional atomic layer deposition. SALD can be used to grow films in the atomic layer deposition or chemical vapor deposition regimes, depending on the extent of precursor intermixing. Precursor intermixing is strongly influenced by the SALD head design and operating conditions, both of which affect film growth in complex ways, making it difficult to predict the growth regime prior to depositions. Here, we used numerical simulation to systematically study how to rationally design and operate SALD systems for growing thin films in different growth regimes. We developed design maps and a predictive equation allowing us to predict the growth regime as a function of the design parameters and operation conditions. The predicted growth regimes match those observed in depositions performed for various conditions. The developed design maps and predictive equation empower researchers in designing, operating, and optimizing SALD systems, while offering a convenient way to screen deposition parameters, prior to experimentation.

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Density Functional Theory (DFT)-enhanced computational fluid dynamics modeling of substrate movement and chemical deposition process in spatial atomic layer deposition

Cited by 12 publications

References 42 publications

Mechatronic Spatial Atomic Layer Deposition for Closed‐Loop and Customizable Process Control

Mechatronic Spatial Atomic Layer Deposition for Closed‐Loop and Customizable Process Control

Exploring TMA and H2O Flow Rate Effects on Al2O3 Thin Film Deposition by Thermal ALD: Insights from Zero-Dimensional Modeling

Can We Rationally Design and Operate Spatial Atomic Layer Deposition Systems for Steering the Growth Regime of Thin Films?

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