(HIPIMS) Plasmas - Research Departments

Dynamics of High Impulse Power Magnetron Spu:ering (HIPIMS) Plasmas W. Breilmann, C. Maszl, A. Hecimovic, V. Schulz-­‐von der Gathen, M. Böke, J. Benedikt, A. von Keudell Research Department Plasma with Complex Interac<ons Ruhr University Bochum HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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Magnetron spu:ering of materials N. Brenning PSST 21, 025005 (2005) HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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Challenge HPPMS Space ShuKle Heat Shield Re-­‐Entry 1 MW/m2 Rolls Royce Flight Engine HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
Engine Ariane 5 2 …… 500 MW/m2 50 M
W/m
2 10 MW/m
100 MW/m2 1000-­‐2000 MW/m2 (homogeneous) (spokes) Divertor ITER ITER Transients 3
VI characterisScs for dc-­‐MS to HiPIMS plasma Voltage (t) Current (t) 175
600
150
500
U (V)
300
100
75
200
50
100
25
0
0
3.5 kW/cm2 3.5 kW/cm2 2.9 kW/cm2 1.8 kW/cm2 1.5 kW/cm2 1.2 kW/cm2 1 kW/cm2 2.9 kW/cm2 1.8 kW/cm2 1.5 kW/cm2 1.2 kW/cm2 1 kW/cm2 0.75 kW/cm2 0.75 kW/cm2 0.5 kW/cm2 0.15 kW/cm2 0.5 kW/cm2 0.15 kW/cm2 0
20
40
60
t(µs)
80
I (A)
125
400
0
20
40
60
80
t(µs)
C. Maszl, W. Breilmann, J. Benedikt, A. von Keudell, J. Phys. D 47, 224002 (2014) HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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HPPMS-­‐Plasmas -­‐ Improved Material ProperSes -­‐ Example Cr1-­‐xAlxN HPPMS results in smaller grains and smoother films compared to dcMS N.Bagcivan,K.Bobzin,G.Grundmeier,C.Kunze,R.H.Brugnara, Thin Solid Films (2013) hKp://dx.doi.org/10.1016/j.tsf.2013.06.036 HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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HPPMS-­‐Plasmas Azimuthal Movement of Plasma Spokes in ExB direcSon Ehiasarian AP, Hecimovic A, de los Arcos T, New R, Schulz-­‐von der Gathen V, Böke M, et al. Applied Physics LeKers 100, 114101 (2012) Hecimovic A, de los Arcos T, Schulz-­‐von der Gathen V, Böke M, Winter J. Plasma Sources Science and Techonology 21, 035017 (2012) Winter J, Hecimovic A, de los Arcos T, Böke M, Schulz-­‐von der Gathen V. Journal of Physics D: Applied Physics. 46, 084007 (2013) HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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HPPMS-­‐Plasmas Azimuthal Movement of Plasma Spokes in ExB direcSon Ehiasarian AP, Hecimovic A, de los Arcos T, New R, Schulz-­‐von der Gathen V, Böke M, et al. Applied Physics LeKers 100, 114101 (2012) Hecimovic A, de los Arcos T, Schulz-­‐von der Gathen V, Böke M, Winter J. Plasma Sources Science and Techonology 21, 035017 (2012) Winter J, Hecimovic A, de los Arcos T, Böke M, Schulz-­‐von der Gathen V. Journal of Physics D: Applied Physics. 46, 084007 (2013) HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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HPPMS-­‐Plasmas Azimuthal Movement of Plasma Spokes in ExB direcSon Ehiasarian AP, Hecimovic A, de los Arcos T, New R, Schulz-­‐von der Gathen V, Böke M, et al. Applied Physics LeKers 100, 114101 (2012) Hecimovic A, de los Arcos T, Schulz-­‐von der Gathen V, Böke M, Winter J. Plasma Sources Science and Techonology 21, 035017 (2012) Winter J, Hecimovic A, de los Arcos T, Böke M, Schulz-­‐von der Gathen V. Journal of Physics D: Applied Physics. 46, 084007 (2013) HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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Plasma Flares in HiPIMS Ar (630-­‐680 V, 500 A) 300 µs 80 µs HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
P. Ni, C. Hornschuch, M. Panjan, A. Anders Appl. Phys. LeK. 101, 224102 (2012); 180 µs 80 µs 80 µs 80 µs 9
DSMC SimulaSon of a 150 µs HiPIMS pulse for an Al target (J. Trieschmann, T. Mussenbrock) Argon HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
Aluminium 10
Monitoring the Dynamic of Spoke Movement afer S. Gallian, J. Trieschmann, T. Mussenbrock, R.-­‐P. Brinkmann, W. Hitchon, JAP 117 23305 (2015) A. Hecimovic, V. Schulz-­‐von der Gathen, M. Böke, A. von Keudell, J. Winter, PSST (2014) HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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Monitoring the Dynamic of Spoke Movement HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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CorrelaSon to plasma diagnosScs: Ion mass spec and PROES HIDEN EQP ICCD ICCD HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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From pulsed dc-­‐MS to HPPMS plasmas C. Maszl, W. Breilmann, J. Benedikt, A. von Keudell, J. Phys. D (2014) accepted HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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IEDFs during HiPIMS of Ti+ ions 2964 W/cm2 0.98kW/cm2 7
10
Ti+ 6
10
279
Gauss Eshift 1 eV, T=1 eV
Thompson ESBE = 4.9 eV
Sum
5
10
7:1 ? 4
10
5e5/7e4 3
10
Ti2+ 6
10
105
IEDF [a.u.]
10
IEDF [a.u.]
0.5 Pa, Ar 7
269
Eshift=0.5 Te=1
Thompson ESBE = 4.9 eV
sum
? 4
10
1:4 3
10
2
10
1
101
0
10
2e5/8e5 ? ? 2
10
10
0
10
0
20
40
60
80
Energy [eV]
thermalized Ti+ dominant energe<c Ti only 0.1% of ion flux 100
0
20
40
60
80
100
Energy [eV]
Ti+ from spuKer wind dominant energe<c Ti 10% of ion flux Dis<nct energe<c peaks ? HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
15
IEDFs with increasing peak power 20
12
8
HE Ti2+ 16
LE Flu x (a.u)
Ti+ 3.0
2.4
1.8
1.2
HE 4
0.6
0
0.0
3.5 kW/cm2 2.9 kW/cm2 3.5 kW/cm2 2.9 kW/cm2 1.8 kW/cm2 1.5 kW/cm2 1.2 kW/cm2 1.8 kW/cm2 1.5 kW/cm2 1.2 kW/cm2 1 kW/cm2 0.75 kW/cm2 1 kW/cm2 0.75 kW/cm2 0.5 kW/cm2 0.15 kW/cm2 0
5
10
15
20
25
Flu x ( a.u)
LE 0.5 kW/cm2 0.15 kW/cm2 30
35
E (eV)
0
10
20
30
40
50
60
70
E (eV)
Dis<nct HE peak appear only if the HiPIMS plasma is in the „spokes“ regime C. Maszl, W. Breilmann, J. Benedikt, A. von Keudell, J. Phys. D 47, 224002 (2014) HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
16
From pulsed dc-­‐MS to HPPMS plasmas 0.5 Pa, Ar, @3 kW/cm2 Ti+ 40
0.5 Pa, Ar end of the pulse 30
energy (eV)
•  Group of higher energy ions (HE) appears simultaneously with low energy ions (LE) •  LE ions increase in energy at later stages of the HiPIMS pulse •  HE ions remain at constant energy, only the distribu<on broadens 20
10
0
0
20
40
60
80
70
100
Ti2+ 60
Most easiest explana<on Two groups of ions (HE and LE) are created at two dis<nct posi<ons of electrical poten<al energy (eV)
50
40
30
20
10
0
0
C. Maszl, W. Breilmann, J. Benedikt, A. von Keudell, J. Phys. D 47, 224002 (2014) HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
20
40
60
80
100
time (µs)
17
Plasma potenSal model to explain disSnct HE and LE peaks Epot in spoke regime E in homogeneous plasma Epot pot
Ti+ -­‐600 V Ionisa<on Inside DL -­‐20 V magne<c trap „pre-­‐sheath“ ioniza<on zone UIR < 10 eV target sheath Ush = -­‐600 V Ionisa<on Plasma bulk 0 Ti+ Ti EQP ambipolar field + + e-­‐ + e-­‐ + e-­‐ e-­‐ plasma bulk substrate sheath Ush = -­‐2 V E x B C. Maszl, W. Breilmann, J. Benedikt, A. von Keudell, J. Phys. D 47, 224002 (2014) HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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Plasma potenSal model GeneraSon mechanism Epot 0 In HiPIMS, ions are generated from an energe<c flux of spuKered metal ions Iner<a causes posi<ve space charge Ti Ti+ Ti+ Epot in spoke regime Epot in homog. plasma chromium 2“ target HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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Spokes during Chromium Spu:ering Transi<on to homogeneous regime 200
0
50
100
time (µs)
150
200
250
300
350
current
flat probe signal
flat probe signal (a.u.)
150
5 mm 10 mm 1 2 1 current (A)
flat probe EQP ion energy mass spectrometer 50 µm orifice 100
50
t=110 µs 110 mm 20 mm anode cover chromium 2“ target flat probe anode cover energy (eV)
80
t=171 µs 0
60
40
20
0
W. Breilmann, A. Eitrich, C. Maszl, A. Hecimovic, V. Layes, J. Benedikt, A. von Keudell, J. Phys D (2015) HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
0
50
100
150
200
250
300
350
time (µs)
20
Spokes during Chromium Spu:ering -­‐ IEDFs 4
P=0.41 kW/cm2, t=101 µs
Thompson distribution (Es hift = 8 eV)
MB distribution (T=6 eV)
3
LE log (counts)
2
1
(*) 0
-1
-2
3
log(counts)
•  MB distribu<on for T=6eV for ions generated from spuKered neutrals (mean free path ~ 0.8 cm) •  In the spokes regime characteris<c HE contribu<on at 35 eV is visible •  Transi<on from spokes to homogeneous regime causes modifica<on of the LE peak only P=2.43 kW/cm2, t=110 µs
P=2.43 kW/cm2, t=170 µs
Thompson distribution (E shift=3eV)
LE MB distribution (T=6eV)
2
1
HE 0
-1
-2
W. Breilmann, A. Eitrich, C. Maszl, A. Hecimovic, V. Layes, J. Benedikt, A. von Keudell, J. Phys D HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
0
20
40
60
80
100
energy (eV)
21
Conclusion -­‐ Acknowledgements Spokes are at the origin of the good performance of HiPIMS plasmas Spokes are a region of highest ionizaSon rate PLUS of disSnct electrical potenSal => source of energeSc ions In the future •  Measurement of electrical potenSals •  Measurement of electron densiSes in the spokes Thank you for your a:enSon HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
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IEDFs for HiPIMS in the spoke mode of StanSum (log scale) 100 eV Ti+ 0 eV 200 eV Ti2+ 50 µs 0 eV 0.98 kW/cm2 1.2 kW/cm2 HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
1.9 kW/cm2 2.4 kW/cm2 2.9 kW/cm2 23
flat probe direct correla<on of IEDF with spoke regime 10 mm EQP ion energy mass spectrometer 5 mm Measurement of Spokes during Chromium Spu:ering 1
2
1
50 µm orifice 110 mm 200
current
flat probe
100
50
0
20 mm flat probe (a.u.)
current (A)
150
0
50
100
150
200
250
time (µs)
300
350
anode cover chromium 2“ target flat probe anode cover W. Breilmann, A. Eitrich, C. Maszl, A. Hecimovic, V. Layes, J. Benedikt, A. von Keudell, (submiKed) HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
24
substrate target Origin of internal electrical fields along a density gradient in a plasma dc-­‐MS ne ni HiPIMS: local rarefracSon – spoke formaSon ne ni Strong gradients cause → a high ambipolar velocity of charged species if a cri<cal velocity is met → two stream instability is triggered, wave builds up, satura<on at a new equilibrium = double layers ambipolar flow increases ne ni ambipolar field + e-­‐ + e-­‐ + e-­‐ e-­‐ ambipolar flow increases and triggers two-­‐stream instab. ne ni + E x E-­‐field DL HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
accelera<on in double layer Double layers proposed by A. Anders et al. B Appl. Phys. LeK. 103 144103 (2013) Appl. Phys. LeK. 103 054104 (2013) 25
Spokes during Chromium Spu:ering Current (A) 0.054 0.123 0.202 0.349 0.486 0.656 0.875 1.054 1.261 power densi<es in kW/cm2 T. De los Arcos et al. JPD 46, 335201 (2013) HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
1.462 1.643 1.795 26
Spokes during Chromium Spu:ering low power: stochas<c regime 0
50
100
250
300
350
200
current
flat probe
0
50
100
time (µs)
150
200
100
80
0
100
80
60
energy (eV)
energy (eV)
2.45 kW/cm2 t=101 µs 0
100
50
0.41 kW/cm2 350
flat probe (a.u.)
150
current (A)
flat probe (a.u.)
current (A)
50
300
current
flat probe
150
100
250
40
20
60
40
20
0
0
50
100
150
200
time (µs)
HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
250
300
350
0
0
50
100
150
200
250
300
350
W. Breilmann, A. Eitrich, C. Maszl, A. Hecimovic, V. Layes, J. Benedikt, A. von Keudell, (submiKed) 200
high power: spokes regime time (µs)
150
200
time (µs)
27
Model for the potenSal energy distribuSon between target and substrate Epot IZ between target and substrate Epot no spoke between target and substrate Epot substrate HE 0 Cr+ LE Cr Cr+ -­‐20 V magne<c trap „pre-­‐sheath“ ioniza<on zone target sheath UIR < 10 eV -­‐600 V plasma bulk substrate sheath Ush = -­‐2 V Ush = -­‐600 V IZ LE HiPIMS Plasmas | Plasma Days 2015 | A. von Keudell
X ionis. W. Breilmann, A. Eitrich, C. Maszl, A. Hecimovic, V. Layes, J. Benedikt, A. von Keudell, (submiKed) HE anode cover X ionis. chromium 2“ target X ionis. anode cover 28