Modélisation particulaire du plasma magnétron impulsionnel haute puissance Tiberiu MINEA Laboratoire de Physique des Gaz et Plasmas LPGP UMR 8578 CNRS, Université Paris-Sud, 91405 Orsay Cedex, France tiberiu.minea@u-psud.fr
Plasma deposition process Film growth Gas dynamics Particle transport Ionization Sputtering D.J. Christie, J V S T A 23, 330 (2005) D Lundin et al., P S S T 18, 045008 (2009) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 2
Conventional magnetron discharge Metal sputtering wind from the target Energetic Ar backscattering Temperature increases Water cooling Power Magnet Pump Target Local gas rarefaction in the high and dense plasma region due to the wind effect Quartz window r B + + + r B + + Ar Ground shield Rossnagel S M (1988) J. Vac. Sci. Technol. A 6 19 Gas Injection Quartz window Gauge MKS T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 3
High Power Impulse Magnetron Sputtering HiPIMS First Pulsed generator concept V. Kouznetsov, U. S. Patent No. 6,296, 742 B 1 (2001) Pulsed power supply: 0.1 1 khz, 200 A, 1 kv Pulse width: 50 to 200 µs Average pulse power: 50 kw Typical mean power: 500 W DC CMS SINEX 3 power supply by PlasmAdvance HiPIMS T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 4
Outline 1. Dimensional modelling of HiPIMS magnetron plasma (OHIPIC) 2. 2D Charged Species and Sheath evolution 3. a posteriori Monte Carlo 4. Metal Transport (3D I OMEGA) 5. Spokes Modelling ITC LPGP ICARE 6. Conclusions T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 5
2D HiPIMS modelling a posteriori MC 3D Metal modelling Spokes Modelling Magnetron target 2D configuration Debye length n e = 10 13 cm 3 = 10 19 m 3 λ e 10 µm (T e = 4eV) Tiberiu MINEA & Claudiu COSTIN Geometry (x, z) Simulation volume: 2 x 2.5 cm 2 Grids: 201 x 512 401 x 2048 Cell dimensions: x, z = 10 µm!!! 6 million simulation particles Control parameters Time step: t= 5 x 10 12 s 5 x 10 13 s Simulated real time: 3.5 µs!!! T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 6
2D HiPIMS modelling a posteriori MC 3D Metal modelling Spokes Modelling Numerical stability criteria Stability criteria: a < λ De CFL : v e x t< a (Courant, Friedrichs, Lewy) N particle/cell ~ 50 Fluctuation of the net charge density (Rho) Adrien REVEL & Tiberiu MINEA a T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 7
2D HiPIMS modelling a posteriori MC 3D Metal modelling Spokes Modelling HiPIMS Simulation parameters z (mm) symmetry axis Magnetic field structure 25 20 15 10 5 anode 0 0 5 10 15 20 cathode x (mm) free boundary Ionization region Cathode voltage (V) Plasma (e, Ar + ) parameters: Ar gas + Cu target p = 5 mtorr T Ar = 400 K 0-200 -400 Short pulse Pre ionization A (75 ns) A (75 ns) C (3.0 µs) C (3 µs) -600 B (2 µs) B (2.0 µs) 0 1 2 3 4 5 6 t (µs) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 8
2D HiPIMS modelling a posteriori MC 3D Metal modelling Spokes Modelling Fast HiPIMS with pre ionization SHORT & FAST Pulsed Power Supply concept [*] which uses preionization to guarantee the fast rise time of the current, fast fall time of the discharge voltage at the switch off Average Power 80 W Pulse width: ~10 µs Repetition rate: 50 500 Hz U max ~ 1kV I Max : 10 100 A * Ganciu et al, World Patent No. WO 2005/090632. 0 2 4 6 8 10 Pulse time [µs] T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 9
HiPIMS current OHIPIC: Orsay HIgh density plasma Particle In Cell model Experiment OHIPIC simulated discharge current 0 Current 300 0 2 4 6 8 10 Pulse time [µs] 0 1 2 3 4 5 6 Pulse time [µs] 600 T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 10
2D HiPIMS modelling a posteriori MC 3D Metal modelling Spokes Modelling 2D maps of charged particles by OHIPIC A (75 ns); n e = 8 x 10 16 m 3 B (2 µs); n e = 8 x 10 17 m 3 C (3 µs); n e = 5 x 10 18 m 3 25 20 25 25 1.0E6 1.7E10 3.4E10 5.1E10 6.8E10 8.5E10 1.0E6 1.6E11 3.3E11 4.9E11 6.6E11 8.2E11 1.0E6 9.4E11 1.9E12 2.8E12 3.8E12 4.7E12 Ar + density (cm -3 e - density (cm -3 20 ) ) Ar + density (cm -3 ) e - density (cm -3 ) 20 Ar + density (cm -3 ) e - density (cm -3 ) z (mm) 15 10 z (mm) 15 10 z (mm) 15 10 5 5 5 0 20 15 10 5 0 5 10 15 20 x (mm) 0 20 15 10 5 0 5 10 15 20 x (mm) 0 20 15 10 5 0 5 10 15 20 x (mm) Electron density increases x 100 in 3 µs!!! Much localized high density Larger dense plasma=> larger race track To take home! T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 11
2D HiPIMS modelling a posteriori MC 3D Metal modelling Spokes Modelling Axial profile evolution of charged particles by OHIPIC Electron density (cm -3 ) 10 12 10 11 10 10 IR Ionization Region DR Diffusion Region 75 ns 0.5 µs 1.0 µs 1.5 µs 2.0 µs 2.5 µs 3.0 µs Ar + density (cm -3 ) 10 12 10 11 10 10 IR Ionization Region DR Diffusion Region 75 ns 0.5 µs 1.0 µs 1.5 µs 2.0 µs 2.5 µs 3.0 µs 10 9 0 5 10 15 20 25 z (mm) 10 9 0 5 10 15 20 25 z (mm) Highest local density = 2 x n e in Ionization Region (IR) n e in IR = 10 x n e in Diffusion Region (DR) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 12
2D HiPIMS modelling a posteriori MC 3D Metal modelling Spokes Modelling Plasma potential evolution by OHIPIC 0 0 Potential (V) -150-300 -450-600 IR Ionization Region -300 Very high electric field in the sheath 75 ns 0.5 µs 1.0 µs 1.5 µs 2.0 µs 2.5 µs 3.0 µs Potential (V) -150-450 Constant but twice higher field in IR -600 in HiPIMS compared 0.0 0.5 1.0 to 1.5 DC 2.0 z (mm) Very low field in DR DR Diffusion Region 0 5 10 15 20 25 z (mm) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 13
2D HiPIMS modelling a posteriori MC 3D Metal modelling Spokes Modelling eedf evolution in HiPIMS by OHIPIC EEDF (ev -3/2 ) 10-2 10-3 10-4 0 100 200 300 Energy (ev) 75 ns 0.5 µs 1.0 µs 1.5 µs 2.0 µs 2.5 µs 3.0 µs eepf (ev -3/2 ) 10-2 10-3 10-4 10-5 Total volume z < 7.5 mm z > 7.5 mm 0 50 100 150 200 250 300 Energy (ev) 10 cm from target eepf (ev -3/2 ) 10-2 10-3 Total volume z < 7.5 mm z > 7.5 mm P Poolcharuansin and J W Bradley, PSST (2010) 10-4 0 5 10 15 20 25 30 Energy (ev) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 14
Outline 1. Dimensional modelling of HiPIMS magnetron plasma (OHIPIC) 2. 2D Charged Species and Sheath evolution 3. a posteriori Monte Carlo 4. Metal Transport (3D I OMEGA) 5. Spokes Modelling 6. Conclusions T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 15
2D HiPIMS modelling a posteriori MC 3D Metal modelling a posteriori Monte Carlo Spokes Modelling Critical point of Monte Carlo simulations prior knowledge ( guess!!! ) of the force field (interaction potential) Self consistent 2D maps of plasma parameters by OHIPIC simulation z (mm) 10 8 6 4 2 0 Initial condition for test particles 0 5 10 15 20 x (mm) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 16
2D HiPIMS modelling a posteriori MC 3D Metal modelling Spokes Modelling Electron transverse diffusion in HiPIMS On the pulse voltage plateau Drift velocity Transverse Diffusion Race track d 1 d w x = x D ( z z ) 2 dt zz = Electron deconfinement 2in dt HiPIMS?? C. Costin, T. Minea, G. Popa, P S S T (submitted) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 17
Outline 1. Dimensional modelling of HiPIMS magnetron plasma (OHIPIC) 2. 2D Charged Species and Sheath evolution 3. a posteriori Monte Carlo 4. Metal Transport (3D I OMEGA) 5. Spokes Modelling 6. Conclusions T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 18
2D HiPIMS modelling a posteriori MC 3D Metal modelling Monte Carlo code OMEGA Spokes Modelling OMEGA: Orsay MEtal transport in GAses model 1. Define a domain (sputter chamber) 2. Generate sputtered particles one by one randomly from a probability distribution (SED + SAD) 3. DCMS: Particle collision with process gas 4. Analyze the particle s velocity, direction, OMEGA summary 3D treatment of elastic collisions Ti/Ar DCMS discharge No Ti Ti collisions No gas rarefaction See also: K. Van Aeken et al., J. Phys. D 41, 205307 (2008) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 19
2D HiPIMS modelling a posteriori MC 3D Metal modelling Spokes Modelling OMEGA Results & Benchmarking DC 2D LIF measurements of Ti sputtered vdf z= 5 cm, p = 3 mtorr p z= 5 cm, p = 30 mtorr LIF box z= 1 cm, p = 3 mtorr z= 1 cm, p = 30 mtorr z D. Lundin et al., J. Phys. D 46, 175201 (2013) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 20
2D HiPIMS modelling a posteriori MC 3D Metal modelling Ionized OMEGA code Spokes Modelling Assumptions I OMEGA 3D treatment of elastic collisions as in OMEGA Inelastic electron impact ionization 1,2 No Ti-Ti collisions, since n Ti /n Ar < 0.2 No gas rarefaction External input of n e and T e maps 25 1.0E6 9.4E11 1.9E12 2.8E12 3.8E12 4.7E12 20 Ar + density (cm -3 ) e - density (cm -3 ) How do we test the accuracy of I OMEGA? z (mm) 15 10 5 [1] P.L. Bartlett and A.T. Stelbovics, At. Data Nucl. Data Tables 86, 235 (2004) [2] H. Deutsch, K. Becker, and T. Märk, Int. J. Mass Spectrom. 271, 58 (2008) 0 20 15 10 5 0 5 10 15 20 x (mm) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 21
2D HiPIMS modelling a posteriori MC 3D Metal modelling I OMEGA: Parametric study Spokes Modelling Ti D. Lundin et al. ICMCTF 2013 Ionized flux fraction Al Cu C Electron density, n e [ 10 17 m -3 ] HiPIMS: D. Lundin and K. Sarakinos, J. Mater. Res. 27, 780 (2012) Ionization model: J.A. Hopwood, Thin Films: Ionized Physical Vapor Deposition, Academic Press, San Diego (2000) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 22
2D HiPIMS modelling a posteriori MC 3D Metal modelling I OMEGA for HiPIMS: Degree of METAL Ionization Spokes Modelling HiPIMS simulated by OHIPIC code Density maps for the three representative instants of the pulse Cathode voltage (V) 0-200 -400-600 Short pulse Pre ionization A (75 ns) A (75 ns) B (2.0 µs) C (3.0 µs) B (2 µs) 0 1 2 3 4 5 6 t (µs) T. Minea et al. S C T (submitted) C (3 µs) Fraction of ionized titanium (A) T e = 5 ev T e = 4 ev T e = 3 ev Ionized flux fraction (Hopwood) a posteriori MC very useful and powerful Fast estimation of the ionization fraction of sputtered vapour and metal ion back attraction (B) Electron density (m -3 ) (C) To take home! T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 23
Outline 1. Dimensional modelling of HiPIMS magnetron plasma (OHIPIC) 2. 2D Charged Species and Sheath evolution 3. a posteriori Monte Carlo 4. Metal Transport (3D I OMEGA) 5. Spokes Modelling 6. Conclusions T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 24
2D HiPIMS modelling a posteriori MC 3D Metal modelling Spokes Modelling Electron burst vs Spokes top view a posteriori MC Fast camera Azimuthal position (mm) 100 80 20 60 40 ns 10 20 Anders et al., J. Appl. Phys. 111, 053304 (2012) N. Brenning et al., J. Phys. D:Appl. Phys, 46, 084005 (2013) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 25
Electron burst side view a posteriori MC Fast camera Anders, Ni, and Rauch 1 2 4 9 19 40 PRELIMINARY y (mm) 100 ns 5 10 z (mm) C. Costin & T. Minea T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 26
Pseudo 3D PIC: Azimuthal PIC MCC 2D (x,z) PIC MCC A. Revel, C. Costin,T. Minea (in preparation) 2D (y,z) PIC MCC with frozen (x,z) field map T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 27
Race track e emission by Pseudo 3D PIC Case 1: Secondary electrons released mainly from the race track (γ = 0.1) Case 2: Secondary electrons localized over emission by 10% Spokes formation!!! T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 28
Pseudo 3D PIC Side view of spokes flares Fast camera Anders, Ni, and Rauch PIC MCC A. Revel, C. Costin,T. Minea (in preparation) T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 29
Pseudo 3D PIC : time average density Instantaneous Electron density integrated over 1 µs Fast camera NO spokes signature at µs time scale! Anders, Ni, and Rauch T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 30
Spokes origin Anders et al. ion impact on the target (dependency with the gas mass and target sublimation energy) Brenning et al. critical ionization velocity (CIV) when plasma moves with respect to background gas Pflug et al. plasma instabilities eus2 M Costin & Minea Burst of electron released from the cathode surface, close to the race track v = iit. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 31
Conclusions Particle simulations bring microscopic information in space and time on plasmas species (densities, potential, eedf, etc.) This knowledge of plasma can be exploited further to deduce transport parameter (electron diffusion across the magnetic field), instabilities, metal transport and ionization, kinetic channels, etc. Reactivity in HiPIMS is only initiated in the high power pulse phase, but it continues in the afterglow, by different reaction channels, namely negative ions T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 32
Contributors France Lise CAILLAULT Catalin VITELARU Daniel LUNDIN Adrien REVEL Sweden Nils BRENING Daniel LUNDIN Romania Claudiu COSTIN Catalin VITELARU Mihai GANCIU Thanks you all for your attention! T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 33
THANKS to all of you!!! Interuniversity Attraction Poles (IAP) Phase VII P7/34 T. Minea Journées Plasmas Froids 2013 / Oct. 17, 2013 34/35