[PPT] - Time resolved LIF studies on sputtered atoms velocity distribution PowerPoint Presentation

SLIDE 1

Time resolved LIF studies on sputtered atoms velocity distribution function

13th FLTPD

13/05/2019 Ludovic de Poucques, Mikaël Desecures, Abderzak El Farsy, Jamal Bougdira Institut Jean Lamour, NANCY, FRANCE

SLIDE 2

Outline

Experimental setup (S9-S18) : TR-TDLIF (Time Resolved-Tunable Diode Laser Induced Fluorescence)

Ludovic de Poucques –13th FLTPD – 13/05/2019

1 Velocity distribution function of sputtered Ti atoms (S33-S38) Velocity distribution function of sputtered W atoms (S19-S32)

Optical arrangement, time resolution Analysis of the TR-TDLIF signal : calculation of Flux velocity distribution function (FVDF) of energetic and thermalized populations. Study of Ar/He gas mixture effect on the transport of W atoms. Analysis of the TR-TDLIF signal : highlights an intermediate regime of transport between ballistic (energetic atoms) and diffusive (thermalized atoms) ones, named quasi-diffusive regime of transport (quasi-thermalized atoms).

Introduction (S2-S8)

Magnetron sputtering, HiPIMS, objectives of our work.

SLIDE 3

Introduction

Ludovic de Poucques –13th FLTPD – 13/05/2019

2 Magnetron sputtering

Conventional magnetron sputtering (dc-MS or rf-MS) :

Developed since the 70’s for microelectronics applications
Nowadays established and widely used method for thin films growth (thin films of materials

such as metals, oxides, nitrides, ceramics, etc) + + + Sputtering of the target (W or Ti) Racetrack on the target n n n Plasma ions Sputtered atoms due to : V E B

B

Deposition on the substrate E : cathode voltage B : permanent magnets

SLIDE 4

Introduction

Ludovic de Poucques –13th FLTPD – 13/05/2019

3 Magnetron sputtering

Conventional magnetron sputtering (dc-MS or rf-MS) : HiPIMS : High Power Impulse Magnetron Sputtering (has emerged in the late 90’s)

In dc-MS or rf-MS : ionization degree of sputtered atoms is weak (~1%).

Sputtered atoms remain mainly neutral atoms (between target and substrate) (ionized sputtered atoms do not contribute to the deposition) The high level of expectations regarding new applications (e. g. deposition on complex shape : 3D) requires to ionize sputtered neutral atoms (difficult to control : trajectories and energies)

SLIDE 5

Introduction

Ludovic de Poucques –13th FLTPD – 13/05/2019

4 HiPIMS

high power (a few kW.cm-2) during short pulses (tens of µs) to avoid the cathode
verheating and arc formation (dc-MS : a few 10 W.cm-2).
Plasma density : 1012 - 1013 cm-3 (dc-MS : ~1011 cm-3).
Ionization degree of the sputtered particles : usually ≥ 50 % (dc-MS : ~1 %).

Ion energy and trajectory can be controlled by polarizing the substrate, while neutrals are difficult to control. However, a significant fraction of sputtered neutral atoms remains and may influence thin film properties. Deposition on complex shape Cu Si

SLIDE 6

Introduction

Ludovic de Poucques –13th FLTPD – 13/05/2019

5 Objectives

Transport : function of “p × d”, gas mixture, σ(ε), ionization

Anode Magnetron cathode

V

Energetic atoms Substrate Thermalized atoms

Number of collisions pressure × distance ε : several eV (Thomson’s distribution) ε : a few 0.01 eV Balistical transport: Energetic atoms (EN) Diffusive transport: Thermalized atoms (TH) collisions Therefore, the knowledge of the properties of incoming film-forming neutral species (study of atoms transport) is required for a better understanding of the HiPIMS deposition process …. One approach to study sputtered atoms transport is the experiment (TR-Laser diagnostics)

SLIDE 7

Introduction

Ludovic de Poucques –13th FLTPD – 13/05/2019

6 Objectives

Literature : some TR laser measurements on neutral sputtered atoms in HiPIMS

Ex. 1 : Palmucci M. et al., JAP 114, 113302 (2013)

TR-LIF measurements with a dye laser (pumped by Nd:YAG laser at 532 nm) : 305 ≤ λ ≤ 330 nm (DCM dye) LIF : space-resolved measurements In this work : distribution of v// is considered And the laser linewidth is ~0.8 pm (~Doppler broadening) Diode Laser (high spectral resolution : < 0.01 pm)

SLIDE 8

Introduction

Ludovic de Poucques –13th FLTPD – 13/05/2019

7 Objectives

Most of laser experiments : distribution of v// is considered (vr) Ti

Ex. 2 : Sushkov V. et al., PSST 22, 015002 (2013)

TR-TDLAS measurements with a single mode DL (Toptica Photonics DL 100) : λ = 398.18 nm LAS : information is averaged along laser beam which is not suitable to probe an inhomogenous plasma like in magnetron discharge (close to the target and/or at very low pressure) Literature : some TR laser measurements on neutral sputtered atoms in HiPIMS z=7 cm

SLIDE 9

Introduction

Ludovic de Poucques –13th FLTPD – 13/05/2019

8 Objectives

Axial laser beam

W Ti knowing that the transport of atoms is from the target toward the substrate : TR-TDLIF (velocity component ⊥ to the target vz). TR- axial VDF (z, t), z = the distance from the target. calibration by means of TR-TDLAS to get absolute values (in conditions where the sputtered vapor can be considered as homogeneous : TH, p, z, t). Our work : characterize sputtered neutral atoms (W, Ti) transport in HiPIMS process.

SLIDE 10

Outline

Experimental setup (S9-S18) : TR-TDLIF (Time Resolved-Tunable Diode Laser Induced Fluorescence)

Ludovic de Poucques –13th FLTPD – 13/05/2019

Velocity distribution function of sputtered Ti atoms (S33-S38) Velocity distribution function of sputtered W atoms (S19-S32)

Optical arrangement, time resolution Analysis of the TR-TDLIF signal : calculation of Flux velocity distribution function (FVDF) of energetic and thermalized populations. Study of Ar/He gas mixture effect on the transport of W atoms. Analysis of the TR-TDLIF signal : highlights an intermediate regime of transport between ballistic (energetic atoms) and diffusive (thermalized atoms) ones, named quasi-diffusive regime of transport (quasi-thermalized atoms).

Introduction (S2-S8)

Magnetron sputtering, HiPIMS, objectives of our work.

SLIDE 11

Experimental setup

9 Optical arrangement

Ludovic de Poucques –13th FLTPD – 13/05/2019

SLIDE 12

10

Ludovic de Poucques –13th FLTPD – 13/05/2019

Experimental setup

Optical arrangement

DL beam is split into two parts with a beam splitter

SLIDE 13

11 The 1st beam (20 %=4 mW) is guided to a Fabry–Pérot interferometer (∆ν=1 GHz free spectral range) to perform a calibration of the laser wavelength scan (∆λlaser(t)).

Experimental setup

Optical arrangement

Ludovic de Poucques –13th FLTPD – 13/05/2019

SLIDE 14

12

Experimental setup

Optical arrangement

Ludovic de Poucques –13th FLTPD – 13/05/2019

The 2nd beam (80 %=16 mW) :

launched into the discharge chamber
oriented normally to the target surface

for vz measurements

towards the racetrack center (R0=1,3

cm), where sputtering of atoms is mostly localized

SLIDE 15

13 Doppler’s relation :

∆λ λ λ λ λ c

Vz=0 : λlaser=λ0=λtransition Vz>0 : λlaser>λ0 (toward the substrate) Vz<0 : λlaser<λ0 (backscattering)

Experimental setup

Optical arrangement

Ludovic de Poucques –13th FLTPD – 13/05/2019

SLIDE 16

14 Detection system + laser beam section Probed volume ≈ 3 mm3 Reliable comparisons of VDF(z) : Detection system is fixed Magnetron cathode is moved by means of a bellows+linear translator system

Experimental setup

Optical arrangement

Ludovic de Poucques –13th FLTPD – 13/05/2019

SLIDE 17

15

Asymmetric current ramp (5 Hz) Wavelength:

λ1 λ2 λ3 λ180

Pulse number: Time Current

Ludovic de Poucques –13th FLTPD – 13/05/2019

Experimental setup

Time resolution

SLIDE 18

15

Asymmetric current ramp (5 Hz) Wavelength:

λ1 λ2 λ3 λ180

Pulse number: Time Current HiPIMS period n° 1: TR-TDLIF at λlaser=λ1 =λ1 2: λlaser=λ1 +0.077pm =λ2 3: λlaser=λ1 +2×0.077pm =λ3 180: λlaser=λ1 + 179×0.077pm =λ180

Experimental setup

Time resolution

∆λ during one HiPIMS period 1 ms ~ 14 180 0.077 pm Doppler velocity increment is only ∆vz~60 m/s for Ti (30 m/s for W)

Ludovic de Poucques –13th FLTPD – 13/05/2019

SLIDE 19

16

Asymmetric current ramp (5 Hz) Wavelength:

λ1 λ2 λ3 λ180

Pulse number: Time Current

40 80 120 160

Time (µs)

Signal de TD-LIF

Time (ms)

Experimental setup

Time resolution

Ludovic de Poucques –13th FLTPD – 13/05/2019 TR-TDLIF signal

SLIDE 20

17

Asymmetric current ramp (5 Hz) Wavelength:

λ1 λ2 λ3 λ180

Pulse number: Time Current

40 80 120 160

Time (µs)

Signal de TD-LIF 55 56 57 λ57 λ56

Time (ms)

λ55

Time (ms)

Experimental setup

Time resolution

Ludovic de Poucques –13th FLTPD – 13/05/2019 TR-TDLIF signal

SLIDE 21

18

Asymmetric current ramp (5 Hz) Wavelength:

λ1 λ2 λ3 λ180

Pulse number: Time Current

40 80 120 160

Time (µs)

Signal de TD-LIF 55 56 57 λ57 λ56

Time (ms)

λ55

λ++ λ λ ,-°++/ c λ+0 λ λ ,-°+0/ c vz(n°56)=vz(n°55)+∆vz

Temporal evolution

AVDF(0 ≤ t ≤ ~1 ms)

Time (ms)

Experimental setup

Time resolution

Ludovic de Poucques –13th FLTPD – 13/05/2019 TR-TDLIF signal

SLIDE 22

Outline

Experimental setup (S9-S18) : TR-TDLIF (Time Resolved-Tunable Diode Laser Induced Fluorescence)

Ludovic de Poucques –13th FLTPD – 13/05/2019

Velocity distribution function of sputtered Ti atoms (S33-S38) Velocity distribution function of sputtered W atoms (S19-S32)

Optical arrangement, time resolution Analysis of the TR-TDLIF signal : calculation of Flux velocity distribution function (FVDF) of energetic and thermalized populations. Study of Ar/He gas mixture effect on the transport of W atoms. Analysis of the TR-TDLIF signal : highlights an intermediate regime of transport between ballistic (energetic atoms) and diffusive (thermalized atoms) ones, named quasi-diffusive regime of transport (quasi-thermalized atoms).

Introduction (S2-S8)

Magnetron sputtering, HiPIMS, objectives of our work.

SLIDE 23

VDF of sputtered W atoms

19 Analysis of the TR-TDLIF signal

Ludovic de Poucques –13th FLTPD – 13/05/2019

i % Δλ(pm)

182W

26,50

0.16 pm

183W

14,31 0 pm

184W

30,64 0.14 pm

186W

28,43 0.40 pm

4 isotopes Experimentally poorly studied Numerous applications in thin layer deposition (ex : WC and WOX) First wall material in fusion devices Interesting case in term of sputtered atoms transport, considering its atomic mass (directivity and energy transfer) planar balanced magnetron cathode equipped with a 5 cm diameter W target

SLIDE 24

20

9 pm

200 pulses ~ 6. 105 points → 0.5 µs → 0.045 pm (~∆vz=30 m/s)

λlaser scan (~ 3Hz)

λ0=407.436 nm Resonant scheme : λLIF(t)= λlaser(t)

VDF of sputtered W atoms

Analysis of the TR-TDLIF signal

Ludovic de Poucques –13th FLTPD – 13/05/2019

Ton/Toff : 7.5 µs/1.5 ms A short Td (7.5 µs) was set in order to study the transport of W atoms with limited disturbances linked to the plasma (strong optical emission and W atoms production).

no DL available to probe the W’s ground state Sufficiently low laser powers (saturation effect)

SLIDE 25

21 2D-image of a typical TR-TDLIF Signal : wavelenght resolved (or velocity resolved) in abscissa and time resolved in ordinate In order to situate the origin ∆λ=0 (vz=0 or λ0ref), the TR-TDLIF signal was measured at a sufficiently long time (t~1ms) from the discharge onset, so that most

f the sputtered W atoms are thermalized.

vz=0 is determined at the maximum of the Gaussian fitting the TH population of one of the isotopes (arbitrarily the isotope 183W was chosen) TH EN

VDF of sputtered W atoms

Analysis of the TR-TDLIF signal

Ludovic de Poucques –13th FLTPD – 13/05/2019

DISCHARGE

SLIDE 26

22

Δλ=1 pm

500 1000 1500 0.00 2.50x10

3

5.00x10

3

7.50x10

3

1.00x10

2

1.25x10

2

TR-TDLIF signal (V) t (µs)

HiPIMS period n°70

Δλ=λlaser-λ0=1 pm (vz=700 m/s for 183W isotope)

2
1

1 2 3 4 5 6 7

2

2 4 6 8

t = 40 µs t = 20 µs

10 20 30

TR-TDLIF signal (mV)

∆λ = λlaser-λref(

183W) (pm)

v (m s

1)
1000

1000 2000 3000 4000 5000

40 μs 20 μs

Doppler profil at given time

VDF of sputtered W atoms

Analysis of the TR-TDLIF signal

Ludovic de Poucques –13th FLTPD – 13/05/2019

DISCHARGE

SLIDE 27

23

1 2 3 4 5 * 183W * 182W * 184W * 186W

t = 40 µs t = 20 µs t = 200 µs

* gaussian

5 10 15

TR-TDLIF signal (mV)

2
1

1 2 3 4 5 6 7

2 4 6

∆λ = λlaser-λref(

183W) (pm)

vz (m s

1)
1000

1000 2000 3000 4000 5000

VDF of sputtered W atoms

Analysis of the TR-TDLIF signal

Ludovic de Poucques –13th FLTPD – 13/05/2019

EN BALISTICAL regime of transport EN + TH MIXTE TH DIFFUSIVE Data analysis: 2 groups of 4 Gaussians → atoms velocity distribution function (AVDF) TH EN TH and EN : much different properties of transport → better represented by their flux (v)

SLIDE 28

24 Flux VDF

Z=2 cm ; 4 Pa ; Ton/Toff : 7.5 μs/1.5 ms ; 200 W cm-2

EN TH FVDF(vz) = AVDF(vz) × vz (W183 x 100 / 14.31 : natural abundance)

VDF of sputtered W atoms

Ludovic de Poucques –13th FLTPD – 13/05/2019

SLIDE 29

25

0.5 1.0 1.5 2.0

[Wrel]TH [Wrel]EN [Wrel]TOT

[Wrel] (10

3Vcms

1)

0.5 1.0 1.5

(Φrel)TH

(Φrel)EN (Φrel)TOT

Φrel (10

6Vcm 2s

2)

20 40 60 80 100 120 140 160 4 8 12 16 <Ez>EN=0.5M<vz

2>(eV)

t (µs)

EN TH

Z=2 cm ; 4 Pa ; Ton/Toff : 7.5 μs/1.5 ms ; 200 W cm-2

VDF of sputtered W atoms

Flux VDF

Ludovic de Poucques –13th FLTPD – 13/05/2019

M Desecures, L de Poucques, T Easwarakhanthan, J Bougdira, Applied Physics Letters, vol. 105 (2014) n°181120. M Desecures, L de Poucques, J Bougdira, Plasma Sources Science & Technol., vol. 26 (2017) n°025003.

FVDF(vz) = AVDF(vz) × vz (W183 x 100 / 14.31 : natural abundance) Vz>0

SLIDE 30

Outline

Experimental setup (S9-S18) : TR-TDLIF (Time Resolved-Tunable Diode Laser Induced Fluorescence)

Ludovic de Poucques –13th FLTPD – 13/05/2019

Velocity distribution function of sputtered Ti atoms (S33-S38) Velocity distribution function of sputtered W atoms (S19-S32)

Optical arrangement, time resolution Analysis of the TR-TDLIF signal : calculation of Flux velocity distribution function (FVDF) of energetic and thermalized populations. Study of Ar/He gas mixture effect on the transport of W atoms. Analysis of the TR-TDLIF signal : highlights an intermediate regime of transport between ballistic (energetic atoms) and diffusive (thermalized atoms) ones, named quasi-diffusive regime of transport (quasi-thermalized atoms).

Introduction (S2-S8)

Magnetron sputtering, HiPIMS, objectives of our work.

SLIDE 31

26 Study of He effect on W atoms transport

z=5 cm ; 4 Pa

z=5 cm ; 8 Pa z=9 cm ; 4 Pa

20 40 60 80

0.0 4.0x10

9

8.0x10

9

1.2x10

10

1.6x10

10

2.0x10

10

Total flux (cm

2)

% He in Ar/He mixture Ton/Toff: 7.5 μs/1.5 ms ; 200 W/cm2

Total Flux directed towards the substrat (vz>0): Number of atoms deposited during a HiPIMS period

Ludovic de Poucques –13th FLTPD – 13/05/2019

VDF of sputtered W atoms

SLIDE 32

27 Study of He effect on W atoms transport

Ton/Toff: 7.5 μs/1.5 ms ; 200 W/cm2

z=5 cm ; 4 Pa

z=5 cm ; 8 Pa z=9 cm ; 4 Pa

20 40 60 80

0.0 4.0x10

9

8.0x10

9

1.2x10

10

1.6x10

10

2.0x10

10

Total flux (cm

2)

% He in Ar/He mixture

0.00 0.05 0.10 0.15 0.20 0.25 deposition 5 cm ; 4 Pa deposition 5 cm ; 8 Pa deposition 9 cm ; 4 Pa

Deposition rate (µm/hr) Measurements on metastable level are well representative of the → total deposited particles in HiPIMS process (ions + neutrals) Study of neutral atoms kinetic considering time evolution of metastable state flux VDF Total Flux directed toward the substrat (vz>0): Number of atoms deposited during a HiPIMS period

Ludovic de Poucques –13th FLTPD – 13/05/2019

VDF of sputtered W atoms

SLIDE 33

28

4 Pa ; 200 W/cm2 Ton/Toff: 7.5 μs/1.5 ms

Close to the target z=1.3 cm Sputtering Few collisions

Ludovic de Poucques –13th FLTPD – 13/05/2019

VDF of sputtered W atoms

Study of He effect on W atoms transport

0%He

FVDF (part. cm-3)

80%He FVDF (part. cm-3)

SLIDE 34

29 Close to the target z=1.3 cm Sputtering Few collisions

VDF of sputtered W atoms

Study of He effect on W atoms transport

Ludovic de Poucques –13th FLTPD – 13/05/2019

4 Pa ; 200 W/cm2 Ton/Toff: 7.5 μs/1.5 ms

0%He

FVDF (part. cm-3)

80%He FVDF (part. cm-3)

Effective sputtering even at 80% He

(no sputtering at 100% He)

Ionization energy Ar = 15.8 eV He = 23.0 eV

1234 5%78 1234 %78 =0.9

SLIDE 35

30

4 Pa ; Ton/Toff: 7.5 μs/1.5 ms ; 200 W/cm2

Distance z=5 cm from the target Transport More collisions

VDF of sputtered W atoms

Study of He effect on W atoms transport

Ludovic de Poucques –13th FLTPD – 13/05/2019

0%He 40%He 80%He

FVDF (part. cm-3) FVDF (part. cm-3) FVDF (part. cm-3)

SLIDE 36

31

4 Pa ; Ton/Toff: 7.5 μs/1.5 ms ; 200 W/cm2

Transport improvement with %He

1234 5%78 1234 %78 =3

Distance z=5 cm from the target Transport More collisions

VDF of sputtered W atoms

Study of He effect on W atoms transport

Ludovic de Poucques –13th FLTPD – 13/05/2019

0%He 40%He 80%He

FVDF (part. cm-3) FVDF (part. cm-3) FVDF (part. cm-3)

~15 collisions with Ar ~100 collisions with He Energy transfers W/Ar → Ef/Ei = 0.70 (30%) W/He → Ef/Ei = 0.98 (2%) Thermalization (W with 〈4 eV〉)

SLIDE 37

32

VDF of sputtered W atoms

Study of He effect on W atoms transport

Ludovic de Poucques –13th FLTPD – 13/05/2019

20 40 60 80

0.0 5.0x10

4

1.0x10

5

1.5x10

5

2.0x10

5

2.5x10

5

Total deposited energy (part cm

3eV)

% He in Ar/He

AN TH TOTAL

20 40 60 80 0.0 5.0x10

9

1.0x10

10

1.5x10

10

2.0x10

10

Total flux (cm

2)

% He in Ar/He

TOTAL DEPOSITED FLUX DURING 1 HiPIMS PERIOD TOTAL DEPOSITED ENERGY DURING 1 HiPIMS PERIOD Z= 5 cm 4 Pa ; 200 W/cm2 Ton/Toff: 7.5 μs/1.5 ms

9 t 1 2 m < vz

AVDF vz, t CD

dvz

Direct characterization of deposited atoms properties Conclusion : could be exploited to tune thin film properties and for process optimization

SLIDE 38

Outline

Experimental setup (S9-S18) : TR-TDLIF (Time Resolved-Tunable Diode Laser Induced Fluorescence)

Ludovic de Poucques –13th FLTPD – 13/05/2019

Velocity distribution function of sputtered Ti atoms (S33-S38) Velocity distribution function of sputtered W atoms (S19-S32)

Optical arrangement, time resolution Analysis of the TR-TDLIF signal : calculation of Flux velocity distribution function (FVDF) of energetic and thermalized populations. Study of Ar/He gas mixture effect on the transport of W atoms. Analysis of the TR-TDLIF signal : highlights an intermediate regime of transport between ballistic (energetic atoms) and diffusive (thermalized atoms) ones, named quasi-diffusive regime of transport (quasi-thermalized atoms).

Introduction (S2-S8)

Magnetron sputtering, HiPIMS, objectives of our work.

SLIDE 39

33 Analysis of the TR-TDLIF signal

Resonance transition at λ0=398.176 nm Ground state 3d24s2 (3F2):0 eV ↔ 3d2(3F)4s4p(1P°):3.1129 eV

2.7 Pa ; z=1.3 cm Ton/Toff: 10 μs/1 ms 350 W/cm2

VDF of sputtered Ti atoms

Ludovic de Poucques –13th FLTPD – 13/05/2019

SLIDE 40

34

2

2 4 6 8 1 2 3 4 5

2

2 4 6 8 1 2 3 4 5

TR-TDLIF measurement (cm-4.s) TH EN ×107

10.7 µs Atoms velocity (km.s-1)

TH

102 µs

×107

2.7 Pa ; z=1.3 cm Ton/Toff: 10 μs/1 ms 350 W/cm2

Analysis of the TR-TDLIF signal

Resonance transition at λ0=398.176 nm Ground state 3d24s2 (3F2):0 eV ↔ 3d2(3F)4s4p(1P°):3.1129 eV

VDF of sputtered Ti atoms

Ludovic de Poucques –13th FLTPD – 13/05/2019

SLIDE 41

35

Ludovic de Poucques –13th FLTPD – 13/05/2019

Analysis of the TR-TDLIF signal

Resonance transition at λ0=398.176 nm Ground state 3d24s2 (3F2):0 eV ↔ 3d2(3F)4s4p(1P°):3.1129 eV

VDF of sputtered Ti atoms

2

2 4 6 8 1 2 3 4

2

2 4 6 8 0.0 0.8 1.6 2.4 3.2

×10

7

23 µs

×10

7

17 µs Atoms velocity (km.s

1)

TR-TDLIF measurement (cm

4.s)

SLIDE 42

36

2

2 4 6 8 1 2 3 4

2

2 4 6 8 0.0 0.8 1.6 2.4 3.2

×10

7

experimental AVDF TH QTH EN Total fit

EN

23 µs

TH QTH

×10

7

17 µs Atoms velocity (km.s

1)

TR-TDLIF measurement (cm

4.s)

3rd population

Ludovic de Poucques –13th FLTPD – 13/05/2019

Analysis of the TR-TDLIF signal

VDF of sputtered Ti atoms

A el Farsy, J Ledig, M Desecures, J Bougdira, L de Poucques, Plasma Sources Science & Technol., vol. 28 (2019) n° 035005.

SLIDE 43

37

2

2 4 6 8 1 2 3 4

2

2 4 6 8 0.0 0.8 1.6 2.4 3.2

×10

7

experimental AVDF TH QTH EN Total fit

EN

23 µs

TH QTH

×10

7

17 µs Atoms velocity (km.s

1)

TR-TDLIF measurement (cm

4.s)

〈vz〉 ~ 1.5 km.s-1 〈Ez〉 ~ 0.5 eV 〈vz〉 ~ 1 km.s-1 〈Ez〉 ~ 0.2 eV QTH atoms VDF is anisotropic (〈vz〉QTH > 0 ) and 〈Ez〉QTH decreases from ~0.5 eV to ~0.05 eV (〈Ez〉TH=0.03 eV ; 〈vz〉TH =0).

Analysis of the TR-TDLIF signal

VDF of sputtered Ti atoms

3rd population

Ludovic de Poucques –13th FLTPD – 13/05/2019

A el Farsy, J Ledig, M Desecures, J Bougdira, L de Poucques, Plasma Sources Science & Technol., vol. 28 (2019) n° 035005.

SLIDE 44

38

2

2 4 6 8 1 2 3 4

2

2 4 6 8 0.0 0.8 1.6 2.4 3.2

×10

7

experimental AVDF TH QTH EN Total fit

EN

23 µs

TH QTH

×10

7

17 µs Atoms velocity (km.s

1)

TR-TDLIF measurement (cm

4.s)

EN atoms (~〈3 eV〉) Balistical transport Anisotropic AVDF Collisions Collisions QTH atoms quasi-diffusive transport Anisotropic AVDF TH atoms Diffusive transport Isotropic AVDF

Ludovic de Poucques –13th FLTPD – 13/05/2019

Analysis of the TR-TDLIF signal

VDF of sputtered Ti atoms

~6-7 ~1-3

A el Farsy, J Ledig, M Desecures, J Bougdira, L de Poucques, Plasma Sources Science & Technol., vol. 28 (2019) n° 035005.

SLIDE 45

39

Ludovic de Poucques –13th FLTPD – 13/05/2019

Conclusion and prospects

A TR-TDLIF technique combining spatial (~3 mm3), temporal (~0.5 µs) and spectral (< 0.

pm) resolutions was developed to measure the axial AVDF, axial FVDF and to study the transport of neutral sputtered atoms in a HiPIMS deposition process.

The insight into the spatio-temporal behavior of the film-forming species may be useful to

tune the film physical properties as desired and as input data in modeling plasma deposition processes.

Indeed, with TR- axial VDF measurements, we obtain a direct characterization of the

deposited neutral atoms properties.

Moreover, the analysis of TR- axial Ti atoms VDF measurements highlighted a third

population of atoms (QTH atoms).

SLIDE 46

40

Ludovic de Poucques –13th FLTPD – 13/05/2019

Conclusion and prospects

This diagnostic, originally developed to study HiPIMS process, may be extended with

appropriate DLs to probe any species with rapidly changing AVDF and FVDF in other pulsed plasmas.

Study the reactive HiPIMS deposition process. This work is in progress with a Ti target and

in Ar/N2 gas mixture.

Corroborate laser measurements with deposited thin layers properties, in view of a

potential HiPIMS deposition process optimization.

SLIDE 47

41

Ludovic de Poucques –13th FLTPD – 13/05/2019