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Research Papers: Flows in Complex Systems

Numerical Study of Turbulent Confined Jets Impinging on a Heated Substrate for Thin Film Deposition

[+] Author and Article Information
Harry Nizard

CNRS–UPR 8521,
Laboratoire PROMES,Tecnosud,
Rambla de la Thermodynamique,
Perpignan 66100, France

Adrien Toutant

CNRS–UPR 8521,
Laboratoire PROMES, Tecnosud
Rambla de la Thermodynamique,
Perpignan 66100, France;
Université de Perpignan,
Via Domitia 52 Avenue Paul Alduy,
66860 Perpignan, Cedex 9, France

Françoise Massines

CNRS-UPR 8521,
Laboratoire PROMES, Tecnosud,
Rambla de la Thermodynamique,
Perpignan 66100, France
e-mail: francoise.massines@promes.cnrs

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received March 27, 2013; final manuscript received April 11, 2014; published online July 24, 2014. Assoc. Editor: D. Keith Walters.

J. Fluids Eng 136(10), 101102 (Jul 24, 2014) (12 pages) Paper No: FE-13-1198; doi: 10.1115/1.4027429 History: Received March 27, 2013; Revised April 11, 2014

This paper reports on the study of confined jets and jets interaction in terms of increasing chemical transport. The context of this study is the atmospheric pressure plasma-enhanced chemical vapor deposition, higher thin film growth rate being desired, while maintaining total flow rate as low as possible. Turbulence mixing and enhanced heat transfer are the physical mechanisms identified as being capable of increasing the growth rate at atmospheric pressure. A numerical study of jets impinging on a heated substrate was carried out using quasicompressible Reynolds-Averaged Navier–Stokes (RANS) equations. Abe–Kondoh–Nagano (AKN) low-Reynolds k-ε and standard k-ε models were tested using an unconfined impinging jet at Reynolds number Re = 23,750 for jet diameter to plate-spacing ratios of H/d = 2 and H/d = 6. Results were compared with experimental data from the literature. Based on numerical results and in accordance with existing findings, the AKN low-Reynolds k-ε was shown to be reasonably accurate and was thus chosen for the numerical study. The effects of flow rate, hole diameter and length, jet-to-jet spacing, confinement width, and jet number were investigated numerically for inline jets confined between two vertical planes for jet Reynolds numbers between 810 and 5060. The configurations with the greatest turbulent intensity were studied, with the addition of diluted species transport and consumption. A laminar flow setup with a slot jet (Re = 79.5) was compared to two injection designs consisting of a simple set of 12 impinging gas jets (Rej = 2530; H/d = 3) with and without the adjunction of a wire to break the jets (Rej = 1687; H/d = 2). The two turbulent injection methods improved growth rate by 15%, which mainly resulted from a larger gas heating by the surface due to turbulent heat exchange in the jet impact zone.

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References

Figures

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Fig. 2

Confined and impinging jets. L and H are the confined space dimensions used for the calculation of Jet Reynolds number Rej.

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Fig. 1

Reactive gas flux and main chemical transports to the substrate surface by convection, diffusion, and turbulent diffusion in the case of plane channel gas flow

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Fig. 7

Perspective view of the setup used to study nonimpacting jets and various parameters. The study was carried out in 3D on 1/4 of the presented domain using symmetries along the yz and xz midplanes. Results are plotted along z-axis and y-axis cuts.

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Fig. 6

Experimental setup for the deposition of amorphous SiNxH coatings in homogeneous (subluminescent and/or Townsend) plasmas at atmospheric pressure

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Fig. 3.

Axisymmetric 2D mesh for low-Re AKN model

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Fig. 4

Average velocity profiles along the vertical axis in r = 0, r = 0.5d, r = d, and r = 2.5d for the standard (dashed lines) and low-Re AKN (solid line) k-ε models. Experimental data: Cooper et al. [26] (H/d = 2; Re = 23,000).

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Fig. 5

Nusselt number profiles along the impact surface (in z = 0) for H/d = 6 for the standard (dashed lines) and low-Re AKN (solid line) k-ε models and the standard k-ε models of Behnia et al. [33] and of Merci and Dick [34]. Experimental data: [27-31].

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Fig. 8

Turbulent intensity generated along the jet axis for various flow rate values, d = d0 and ls = 1.5d0

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Fig. 9

Turbulent intensity generated along the jet axis for various jet diameter values, Q = Q0 and ls = 1.5d0

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Fig. 10

Turbulent intensity generated along the jet axis for various slit widths for Q = Q0 and d = d0

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Fig. 11

Profile of turbulent kinetic energy k integrated on the x-y planes and plotted as a function of z. The first profile was obtained for Re = 1270 with default parameters Q = Q0, d = d0, and ls = 1.5d0 (solid line). The subsequent profiles were obtained by reducing d (short dash), increasing Q (long dash), or increasing slit width ls (dotted line), enabling Rej to reach a value of 2230 and 2550.

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Fig. 12

Turbulent intensity along the jet axis for various hole lengths, h, and d = d0. Exit holes are represented in z = 0.

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Fig. 13

Turbulent intensity profile generated in the slit. Cut along the y-axis in z = –5d0 (solid lines), z = –10d0 (dashed lines), and z = –20d0 (dotted lines) for six jets (d = d0, thin lines) and 12 jets (d = 0.71 d0, thick lines) with the same average exit speed Ud. Values of the jet-to-jet spacing lh: 4d0 (six jets) and 2d0 (12 jets) on the left (a), and 8d0 (six jets) and 4d0 (12 jets) in graph (b). Jet exits’ positions on the y-axis are indicated by arrows.

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Fig. 16

The three injection devices: laminar slit injection (a), injection through 12 vertical impinging jets (b), and injection through 12 vertical jets with a wire (c). The study domain represents 1/4 of the system, using two symmetries along the x-z and y-z vertical planes. Plasma zone appears darker, in the horizontal section.

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Fig. 14

Perspective view of the impacting jets and various parameters. The study was carried out in 3D on one-half of the domain using symmetry along the z-x midplane. Results are plotted along the z-axis cut.

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Fig. 15

Turbulent intensity along the jet axis for various impact lengths H and d = d0. The jet exit is represented in z = 0.

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Fig. 21

Growth rate along the x-axis with a sticking coefficient of Cc = 10–3 m/s for the laminar slit injection, 12 vertical impinging jets, and 12 vertical jets with a wire

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Fig. 17

Velocity profile (in m.s–1) as a function of the y-axis at the plasma entrance (x = 7.5d) and 40 μm above the substrate surface for the laminar slit injection (solid line), 12 vertical impinging jets (dashed line), and 12 vertical jets with a wire (dotted line)

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Fig. 18

Velocity field (up) and turbulent intensity (down) along the x-z plane in the center of the jet in the laminar slit injection (a), 12 vertical impinging jets (b), and 12 vertical jets with a wire (c) for y in the axis of the jet

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Fig. 19

Turbulent diffusion coefficient in m2/s (up) and molecular diffusion coefficient (down) along the x-z plane in the jets' axis for the laminar slit injection (a), 12 vertical impinging jets (b), and 12 vertical jets with a wire (c) setups

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Fig. 20

Temperature profile (in K) as a function of the y-axis at the plasma entrance (x = 7.5d) and at 0.5 mm = H/2 above the substrate surface (in the middle of gap height) for the laminar slit injection (solid line), 12 vertical impinging jets (dashed line), and 12 vertical jets with a wire (dotted line)

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Fig. 22

Growth rate along the x-axis with a sticking coefficient of Cc = 10–1 m/s for the laminar slit injection, 12 vertical impinging jets, and 12 vertical jets with a wire

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Fig. 23

Images of the obtained growth rate on the x-y plane for the laminar slit injection (a), 12 vertical impinging jets (b), and 12 vertical jets with a wire (c). Each image represents 1/4 of the system, with symmetries along the x = 0 and y = 0 lines.

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