Understanding the relation between stress and surface morphology in sputtered films: Atomistic simulations and experiments

Zepeda-Ruiz, Luis A.; Chason, Eric; Gilmer, George H.; Wang, Yinmin; Xu, Hongwei; Nikroo, A.; Hamza, A. V.

doi:10.1063/1.3246791

Cited by 21 publications

(11 citation statements)

References 18 publications

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“…5 In addition, for large deposition angles our results for the thin-film porosity were found to be in excellent agreement with recent experimental values. 9 In this case for both random and fixed φ we have also found that while the strain is initially compressive, it becomes tensile after the onset of columnar growth for large deposition angles, in good qualitative agreement with the behavior obtained previously by Zepeda-Ruiz et al 9 in sputter-deposition experiments on Be growth with and without substrate bias.…”

Section: Discussionsupporting

confidence: 91%

“…In addition, we find that while the average strain is initially compressive for both random and fixed φ, it becomes tensile after the onset of columnar growth, in good qualitative agreement with recent experimental observations. 9 Our results also indicate that even on MD time-scales a variety of complex dynamical processes including coalescence, large-scale collective events, and budding play a key role in determining the evolution of the surface morphology and microstructure.…”

Section: Introductionsupporting

confidence: 52%

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Large-scale molecular dynamics simulations of glancing angle deposition

Hubartt

Liu

Amar

2013

Journal of Applied Physics

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While a variety of methods have been developed to carry out atomistic simulations of thinfilm growth at small deposition angles with respect to the substrate normal, due to the complex morphology as well as the existence of multiple scattering of depositing atoms by the growing thin-film, realistically modeling the deposition process for large deposition angles can be quite challenging. Accordingly, we have developed a computationally efficient method based on the use of a single graphical processing unit (GPU) to carry out molecular dynamics (MD) simulations of the deposition and growth of thin-films via glancing angle deposition. Using this method we have carried out large-scale MD simulations, based on an embedded-atom-method potential, of Cu/Cu(100) growth up to 20 monolayers (ML) for deposition angles ranging from 50 • to 85 • and for both random and fixed azimuthal angles. A variety of quantities including the porosity, roughness, lateral correlation length, average grain size, strain, and defect concentration are used to characterize the thin-film morphology. For large deposition angles (θ ≥ 80 o) we find well-defined columnar growth while for smaller angles, columnar growth has not yet set in. In addition, for θ = 70 o − 85 o the thinfilm porosity and columnar tilt angles (for fixed azimuthal angle φ) are in reasonable agreement with experiments. We also find that for both random and fixed φ the average strain is initially compressive but becomes tensile after the onset of columnar growth, in good qualitative agreement with recent experimental observations. Our results also indicate that for large deposition angles a variety of complex dynamical processes including coalescence, large-scale collective events, and budding play a key role in determining the evolution of the surface morphology and microstructure.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionsupporting

confidence: 52%

Large-scale molecular dynamics simulations of glancing angle deposition

Hubartt

Liu

Amar

2013

Journal of Applied Physics

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“…At higher growth rates, the films are susceptible to the formation of dendrites or other surface instabilities. Excessive surface roughness can lead to inaccuracy in estimated growth rate and porosity in the film (32). These effects can invalidate the mechanisms for stress generation that are included in the model.…”

Section: Comparison Of Experimental Results With Modelsmentioning

confidence: 99%

Origins of residual stress in thin films: Interaction between microstructure and growth kinetics

2016

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Thin films can develop large residual stresses during their growth that significantly impact their performance. Therefore, there is a need to understand how the stress is related to the developing film structure and underlying kinetic processes. In this work, we describe measurements of stress and the corresponding grain structure during electrodeposition of Ni and Cu films. For Ni deposition, the grain size stays nearly constant during growth and the stress reaches a nearly constant steady-state. For Cu deposition, the grain size grows as the thickness increases and the microstructural evolution affects the evolution of the stress. To remove the effect of subsurface grain growth on the stress, measurements were also done with periodic pauses that allowed the stress induced by grain growth to saturate. We interpret the results in terms of a kinetic model for stress evolution that focuses on the developing boundary between adjacent grains while the film is deposited. The effect of grain growth on stress for different types of microstructural evolution is also discussed. After accounting for the stress from subsurface grain growth, the results are consistent with the model for the dependence on growth rate and grain size at the surface.

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“…In this respect, we use the disappeared vacancy concentration as a surrogate for the stress evolution as previously done in Ref. 25. The number is normalized by the equilibrium GB vacancies in one substrate layer, and its average over five independent simulations is shown in Fig.…”

Section: Stress Control In Polycrystalline Thin Films-reduction In Admentioning

confidence: 99%

Stress control in polycrystalline thin films—reduction in adatoms diffusion into grain boundaries via surfactants

Huang

Xiang³

et al. 2010

Applied Physics Letters

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The diffusion of adatoms into grain boundaries (GBs) of polycrystalline thin film during vapor deposition affects the stress that develops and the film’s subsequent performance. This Letter reports a proposed mechanism of modifying the stress by controlling adatom diffusion into GBs through the use of surfactants. Based on polycrystalline kinetic Monte Carlo simulations of Cu⟨111⟩ thin films with In surfactant, the authors demonstrate that the proposed mechanism is feasible. Further, the authors show that the reduction is due to the decrease in effective adatom diffusivity, which dominates over the increase in adatom concentration.

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Understanding the relation between stress and surface morphology in sputtered films: Atomistic simulations and experiments

Cited by 21 publications

References 18 publications

Large-scale molecular dynamics simulations of glancing angle deposition

Large-scale molecular dynamics simulations of glancing angle deposition

Origins of residual stress in thin films: Interaction between microstructure and growth kinetics

Stress control in polycrystalline thin films—reduction in adatoms diffusion into grain boundaries via surfactants

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