Nichtthermischer HF-Plasmajet, Entladungsregimes und Schichteigenschaften

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1 Nichtthermischer HF-Plasmajet, Entladungsregimes und Schichteigenschaften R. Foest, J. Schäfer, F. Sigeneger, S. Peters, K.-D. Weltmann Leibniz-Institut für Plasmaforschung und Technologie Felix-Hausdorff-Str Greifswald, Germany Phone: Fax: foest@inp-greifswald.de Web: VON D ER ID EE B IS ZU M PROTOT YP

2 Outline al 3. from microplasma to nanostructure Self-organization: Well defined spatiotemporal low frequency motion of microdischarges CFD-simulation: Kinetics of molecules in reactive mixtures Thin film deposition: 4. Structuring of molecular network

3 1. Self-Organization A nice (well-ordered) plasma reduces the irregularity Spatial patterns of microdischarges Anode spots, DBD, Helium (2004) K. H. Schoenbach, M. Moselhy, W. Shi, Plasma Sources Sci. Technol. 13 (2004), 177.

4 1. Self-Organization Periodical movement of Microdischarges or Flow in liquids Observation of steadily rotating discharge (2004) surface charge domains A. Wilson, D. Staack, T. Farouk, A. Gutsol, A. Fridman, B. Farouk, Plasma Sources Sci. Technol. 17 (2008), Helical traveling waves in pipe flow (2007) Ch. C. T. Pringle, R. R. Kerswell, Phys. Rev. Lett. 99 (2007), Four fast streaks of helical mode plotted over one wavelength 170D. and velocity slices across a helical mode taken at the same instant of time but 25D apart (Re=1344)

5 1. Self-Organization Well defined spatiotemporal low frequency motion of microdischarges Revolving Modes in RF and MW Nonthermal Atmospheric Pressure Plasma Jets Schäfer et al. IEEE Trans. Plasma Sci., 99 (2011)

6 1. Thin film deposition Tentative applications: Functional coatings by PE-CVD Coating of 3D forms, corrosion protection / barrier coatings / scratch resistance, biocompatibility Structuring of the molecular network: SiOxCyHz films deposited by an atmospheric pressure plasma source Schäfer, J.; Horn, S.; Foest, R.; Brandenburg, R. ; Vašina, P.; Weltmann, K.-D.; Surf. Coatings Technol. 205 (2011) S330 Smooth delamination Dep. rate 1 nm/s Sharp delamination Dep. rate 2.5 nm/s Fractalized structure Dep. rate 20 nm/s

7 Application Roof module with panorama glass and integrated pv panel 20 kg total weight Polycarbonate Makrolon AG2677 (Bayer MaterialScience, Webasto AG) Advantage: Low mass unbreakable Drawback: UV stability Scratch resistance

8 2. al HMDSO & Argon nt-appj (locked mode) Film deposition Silicon-organic molecule (e.g. HMDSO-Precursor)+Argon al conditions Matching network RF Characterization of SiO x C y H z films Parameter RF-Power Value 10 W Plasma diagnostics Model CFD-Simulation RF-Frequency 27 MHz Argon 1 slm HMDSO 1 % Re appr nm

9 3. Locked modes - Argon Low FA, dr 0.5 mm, dt 1 ms development of a distinctive plasma regime (locked mode) nomenclature and operating diagram of self-organized regimes explanation / hypothesis Focus: locked mode 3 (LM3) LM1, 1 ms

10 3. Electron concentration Line broadening of Balmer H β and H γ Gaussian profile: Instrumental broadg., Doppler broadg. Lorentzian profile: van der Waals broadg., Electron collision broadg. (Stark broadening) counts Balmer β meas. points Voigt profile Gaussian profile Lorentzian profile counts ,8 485,9 486,0 486,1 486,2 486,3 486,4 Balmer γ meas. points Voigt profile Gaussian profile Lorentzian profile λ [nm] 0 434,3 434,4 434,5 434,6 λ [nm] Result: (consistent over 3 different evaluation methods): n e = (3.0±1.2) cm -3 (LM 3)

11 3. Two-dim model Self consistent modelling and analysis of single discharge filament (Ar plasma incl. wall sheaths) comparison n e, T e with experiment (Spectroscopy) Assumptions: Stationary single filament (R = 0.2 mm) 2-dim. axial symm. geometry Length L = 10 mm (electrode center) Taken from experiment: Dissipated total power P ~1.3 W T g = 600 K (between electrodes) Gas flow =0 Equations: Species: e -, Ar*, Ar +, Ar e-atom-reactions, 10 heavy species reactions Continuity equ., Poisson equ., Energy balance, electron-, charge balance at the (diel.) surface Stationary 0D-Boltzmann equation incl. electron-electroninteraction Provides transport- and rate coefficients

12 3. (model) Electron density Maximum n e : cm -3 Structural change in filament (Dielectrics-> wall sheath -> column) Sheath width: 0.15 mm Ionization by electron collision with excited Ar dominant Most abundant ion: Ar 2 + Radial profile n e Axial profiles carrier densities

13 3. Thin film deposition Profiles of film thickness and chemical composition (local): Balance model of the deposition rate depends on the parabolic velocity profiles of the gas flow (left) Agreement with SEM (on right c) IR absorption band at 1276 cm -1 marker of carbon content (b) Maximal film thickness = minimal carbon concentration, SiO 2 nature Low carbon concentration in centre of the foot print (a) [J. Schäfer, R. Foest, A. Quade, A. Ohl, K.-D. Weltmann, J. Phys. D 41 (2008), ]

14 3. CFD Simulation equations Navier-Stokes-Equations: Transport equations: Electrons: Excited Ar: HMDSO: M. Schmidt, M. Maass, Contr. Plasma Phys. 29 (1989), 197 Reaction products: Ar* = [e -, Ar +, Ar 2+, Ar*]

15 3. CFD Simulation Velocity Electrons Excited atoms 1.5 m/s 1.5 m/s 1.5 m/s z [ mm ] r [ mm ] r [ mm ] r [ mm ]

16 3. CFD Simulation HMDSO Reaction products (RP) RP on a target 1.5 m/s 1.5 m/s z [ mm ] r [ mm ] r [ mm ]

17 3. CFD Simulation Deposition and analytical model (2008) Simulated profiles (2011) J. Schäfer, R. Foest et.al., J. Phys. D 41 (2008) Parameter Value RF-Power 7 W Density profiles of reaction products on the target RF-Frequency Argon HMDSO Target (Si) 27 MHz 0.8 slm 0.1 g/h 6 mm

18 3. Scanning XPS (HMDSO - LM) Cps Si(-O) 4 Si(-O) 3 Si(-O) 2 Si(-O) Si-O O-Si-O O-Si-O O Cps Si(-O) Si(-O) Si(-O) Si(-O) Position [mm] O O-Si-O O mm Cps Si(-O) 4 Si(-O) 3 Si(-O) 2 Si(-O) binding energy [ev] SiO x binding procenture 5 0,2 0,3 0,4 0,5 Si/O ratio Binding Energy / ev SiO x -Conformation Si/O

19 3. Dynamic Deposition Scratch Resistive Film Scratch track Uncoated half Coated half 500 nm SiO x on Polycarbonate Taber abraser CS5- felt 1000 u

20 1) Phenomenological Characterization: Low frequency analysis, Range of existence J.Schäfer et al. Plasma Phys. Control. Fusion 51 (2009) ) al Characterization: T g (Capillary) = K n e = (3.0±1.2) cm dim fluiddynamic model: # of filaments J. Schäfer et al., Eur. Phys. J. D 60 (2010) Electron density Gas flow P/W 3) Homogeneous SiO x -films J. Schäfer et al., Eur. Phys. J. D 54 (2009) y [mm] Foot Print / Coating x [mm] [µm] 0,55 0,50 0,45 0,40 0,35 0,30 0,25 0,20 0, h / µm

21 Acknowledgement Contributions: INP: J. Schäfer, F. Sigeneger, S. Horn, M. Becker, D. Loffhagen A. Quade, S. Peters, C. Wilke, K.D. Weltmann Uni Brno: P. Vašina, J. Hnilica, V.Kudrle Uni Kiel: T. Kewitz Uni Greifswald: R. Hippler, A. Hupel Work supported by: DFG - TR 24 Complex Plasmas

22 Contact Leibniz Institute for Plasma Science and Technology e.v. Address: Felix-Hausdorff-Str. 2, Greifswald Tel: , Fax: welcome@inp-greifswald.de, Web: