FORMATION OF DUST PARTICLES AND RELATED PHENOMENA filem. mikikian – dsdp2 – kiel – september 4. th. 2009. formation of dust particles in a plasma why ? where ? evidence and diagnostics

M. MIKIKIAN – DSDP2 – Kiel – September 4th 2009

FORMATION OF DUST PARTICLESFORMATION OF DUST PARTICLES

AND RELATED PHENOMENAAND RELATED PHENOMENA

Maxime Mikikian

M. Cavarroc, L. Couëdel, Y. Tessier, L. Boufendi

GREMI, Groupe de Recherches sur l'Énergétique des Milieux IonisésOrléans - France


FORMATION OF DUST PARTICLES IN A PLASMAFORMATION OF DUST PARTICLES IN A PLASMAWhy ?Why ?Where ?Where ?

EVIDENCE AND DIAGNOSTICS OF DUST PARTICLE FORMATIONEVIDENCE AND DIAGNOSTICS OF DUST PARTICLE FORMATIONElectrical and optical measurementsElectrical and optical measurementsInstabilities induced by dust particle growthInstabilities induced by dust particle growthDesign of singleDesign of single--crystal silicon crystal silicon nanoparticlesnanoparticlesSuccessive generations of dust particlesSuccessive generations of dust particles

SUCCESSIVE GENERATIONS OF DUST PARTICLESSUCCESSIVE GENERATIONS OF DUST PARTICLESDustDust--free region: the voidfree region: the voidSuccessive generations from the voidSuccessive generations from the voidSuccessive generation instabilitiesSuccessive generation instabilitiesVoid instabilities ?Void instabilities ?

CONCLUSIONSCONCLUSIONS

OUTLINEOUTLINE







FORMATION OF DUST PARTICLES : WHY ?FORMATION OF DUST PARTICLES : WHY ?


FORMATION OF DUST PARTICLES : WHY ?FORMATION OF DUST PARTICLES : WHY ?

Presence of reactive gasesSilane

(SiH4

), Methane (CH4

), Acetylene (C2

H2

)

Material erosionTungsten, Graphite, …

New charged species in the plasma

modifications of plasma properties


FORMATION OF DUST PARTICLESFORMATION OF DUST PARTICLES

Reactive gases: SiH4

(microelectronics)

Reactive gases: Hydrocarbon CH4

, C2

H2

(astrophysics, C, CN nanoparticle, DLC)

Sputtering: (industry, fusion)

R.M. Roth et al. Appl. Phys. Lett. (1985)Y. Watanabe et al. Appl. Phys. Lett. (1988)A. Bouchoule

et al. J. Appl. Phys. (1991), Pure Appl. Chem. (1996)

A. Howling et al. Appl. Phys. Lett. (1991)

C. Deschenaux

et al. J. Phys. D: Appl. Phys. (1999)S. Hong et al. Plasma Sources Sci. Technol. (2003)J. Pereira et al. J. Appl. Phys. (2008)I. Stefanovic

et al. New J. Phys. (2003)

K. De Bleecker

et al. Phys. Rev. E (2006)E. Kovacevic

et al. J. Appl. Phys. (2009)

G.S. Selwyn et al. J. Vac. Sci. Technol. A (1989), SiliconG.M. Jellum

et al. J. Appl. Phys. (1990), Aluminium

B. Ganguly

et al. J. Vac. Sci. Technol. A (1993)G. Praburam

et al. J. Vac. Sci. Technol. A (1994)

M. Mikikian

et al. New J. Phys. (2003)C. Arnas


Some references, really NOT EXHAUSTIVE list…


A. Bouchoule

et al. Plasma Sources Sci. Technol. (1993)from R.L. Merlino

et al. Phys. Today (2004)

GLOBAL SCHEME OF DUST PARTICLE FORMATION GLOBAL SCHEME OF DUST PARTICLE FORMATION M. Cavarroc

PhD Thesis Univ. Orléans

(2007)

see also A. Bouchoule

et al. Pure Appl. Chem. (1996)

Aggregation is still an open debate due to the

dust particle chargesee for ex. L. Ravi

et al. Phys. Rev. E (2009)


FORCES : SHAPE OF THE DUST CLOUDFORCES : SHAPE OF THE DUST CLOUDGravity, Electric

force, Ion drag, Neutral

drag, Thermophoresis, Interactions


In natureIn astrophysics

•

Planetary rings, atmospheres (CH4

)•

Interstellar clouds (dark nebulae)

WHERE CAN WE FIND DUSTY PLASMAS ?WHERE CAN WE FIND DUSTY PLASMAS ?

Titan

for ex. C. Szopa

et al. Planet. Space Sci. (2006)

for ex. E. Kovacevic

et al. ApJ

(2005)

Horsehead

Nebula

See Talk of Ella Sciamma

O'Brien at 12:10


In industry

Dust particles harmful(End of 80s –

beginning of 90s)

Surface processing in microelectronics

(cleanliness is a major requirement)

• Thin film deposition•

Etching

G. Selwyn et al. J. Vac. Sci. Technol. A (1989)R.M. Roth et al. Appl. Phys. Lett. (1985)

Use of reactive gases

SputteringDust particle formation

Dust particle clouds



In industry

Dust particles useful(End of 90s)

Dust particle formation (silicon, carbon)

G. Viera



Design of new materialsNanotechnologies

•

Nanostructured

materials• Solar cells (polymorphous silicon)

P. Roca

i Cabarrocas

J. Vac. Sci. Technol. A (1996) • Single electron devices (transistor, memories)

Transistor using silicon nanocrystalsA. Dutta

et al. Jpn. J. Appl. Phys. (2000)

Silicon nanocrystals incorporated in an

amorphous film

CHALLENGEControl the formation and

deposition of grown nanoparticles(size, structure, number, position)


In fusion devicesDust particles harmful

Wall erosionImpurities in the plasma

Radio-toxicity of dust particles

Tore Supra Tokamak


J. Winter, Plasma Phys. Control. Fusion (2004)C. Arnas

et al. J. Nucl. Mater (2009)S.I. Krasheninnikov

et al. Plasma Phys. Control. Fusion (2008)D.L. Rudakov

et al. Rev. Sci. Instrum. (2008)







HOW CAN WE DETECT (EASILY) DUST PARTICLESHOW CAN WE DETECT (EASILY) DUST PARTICLESIN A PLASMA ?IN A PLASMA ?

If dust particle density is high

Important loss of free electrons

Plasma properties are highly affected

Ii

Ie

--- -

--

-

Dust particles collect plasma free electrons and acquire a negative charge (floating potential)

New charged species

Clearly

visible on electrical

and

optical

characteristics


0 200 400 600 800 1000 12001

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

In a sputtering discharge

Time

5'

10'

15' 20'

M. Mikikian, L. Boufendi, A. Bouchoule, H.M. Thomas, G.E. Morfill, A.P. Nefedov, V.E. Fortov

and the PKE-Nefedov

team, New J. Phys. 5, 19 (2003)

ELECTRICAL MEASUREMENTSELECTRICAL MEASUREMENTSCharging process of dust particles is "universal", whatever the chemistry

All types of electrical measurements could be able to detect dust particles

Example of the discharge current (see also L. Boufendi

et al. Appl. Phys. Lett. (2001))

In a silane

based discharge

Decrease induced by the growth of dust particles


Formation of various molecules

N2

, OH, CN, CH, C2

C2

is the indicator of dust particle growth

Swan system 516.52 nm

P = 0.4 mbar Dust

P = 0.8 mbar Dust

P = 1.2 mbar Dust

P = 1.6 mbar Dust0 100 200 300 400 500 600

0

400

800

1200

1600

2000

Time (s)

Inte

nsit

y (a

.u.)

P = 0.4 mbar

P = 0.8 mbar

P = 1.2 mbar

P = 1.6 mbar

C2 consumption for dust particle formation

OPTICAL MEASUREMENTSOPTICAL MEASUREMENTS

M. Mikikian, L. Boufendi, A. Bouchoule, 30th

EPS, ECA Vol. 27A, p. O-3.1B (2003)


When the global charge of the dust particle

cloud is high

Enhancement of the free electron energy

Enhancement of the argon lines

0 1000 2000 3000 4000 5000 60000

0.5

1

1.5

2

2.5

3

Time (s)

Inte

nsit

y (a

.u.)

750.3 763.5 800.6 763.5 / 800.6

10’ 5’ 2’



EPS, ECA Vol. 27A, p. O-3.1B (2003)

A. Bouchoule

et al.Plasma Sources Sci. Technol. (1994)


When the global charge of the dust particle

cloud is high

Enhancement of the free electron energy

Enhancement of the argon lines



EPS, ECA Vol. 27A, p. O-3.1B (2003)

A. Bouchoule

et al. Plasma Sources Sci.

Technol. (1994)

A. Bouchoule

et al.Plasma Sources Sci. Technol. (1994)


ELECTRICAL MEASUREMENTSELECTRICAL MEASUREMENTS

M. Mikikian, M. Cavarroc, L. Couëdel, L. Boufendi, Phys. Plasmas 13, 092103 (2006)

If dust particle density is high Plasma equilibrium is affectedINSTABILITIES

Aggregation

Growth by surface deposition

Time (s)

Amplitud

e of

3H (a.

u.)

M. Cavarroc, M.C. Jouanny, K. Radouane, M. Mikikian, L. Boufendi, J. Appl. Phys 99, 064301 (2006)M. Cavarroc, M. Mikikian, G. Perrier, L. Boufendi, Appl. Phys. Lett. 89, 013107 (2006)


ELECTRICAL MEASUREMENTSELECTRICAL MEASUREMENTS

1.4 1.5 1.6 1.7 1.830

40

50

60

70

80

90

100

110

120

130

Pressure (mbar)A

ppea

ranc

e tim

e (s

)

Appearance time function of pressure, power

High pressure and/or high power = Fast kinetics


0 100 200 300 400 500 600 700 800

0.5

0.55

0.6

0.65

0.7

0.75

0.8

Time (s)

Am

plitu

de (a

.u.)

Beginning of instabilities

Electron attachment on dust particles

Instability beginning

Plasma on

If dust particle density is high Plasma equilibrium is affectedINSTABILITIES

M. Cavarroc, M.C. Jouanny, K. Radouane, M. Mikikian, L. Boufendi, J. Appl. Phys 99, 064301 (2006)M. Cavarroc, M. Mikikian, G. Perrier, L. Boufendi, Appl. Phys. Lett. 89, 013107 (2006)


Appearance:

a few hundreds of ms after plasma ignition

Frequency: from 1 to 3 kHz

Duration: a few ms

DUST PARTICLE GROWTH INSTABILITIES: DUST PARTICLE GROWTH INSTABILITIES: ArAr/SiH/SiH44

M. Cavarroc, M. Mikikian, G. Perrier, L. Boufendi, Appl. Phys. Lett. 89, 013107 (2006)

Aggregation


Nanocrystalaccumulation

Instability

Time (s)

Amplitud

e of

3H (a.

u.) zoom

spectrogram

M. Cavarroc, M.C. Jouanny, K. Radouane, M. Mikikian, L. Boufendi, J. Appl. Phys 99, 064301 (2006)


Appearance:

a few hundreds of ms after plasma ignition

Frequency: from 1 to 3 kHz

Duration: a few ms

DUST PARTICLE GROWTH INSTABILITIES: DUST PARTICLE GROWTH INSTABILITIES: ArAr/SiH/SiH44


Aggregation



Instability

Time (s)

Amplitud

e of

3H (a.

u.) zoom

spectrogram

V dc

(Vol

ts)

V dc

(Vol

ts)

M. Cavarroc, M.C. Jouanny, K. Radouane, M. Mikikian, L. Boufendi, J. Appl. Phys 99, 064301 (2006)


Before instability During instability After instability

Nanocrystals Nanocrystals & dust particles

Dust particles

In Ar/SiH4

this instability is induced by nanocrystal

agglomeration(fast change of the global charge carried by the dust cloud)

~ Attachment induced ionization instability observed in electronegative gases(see W.L. Nighan

et al. Phys. Rev. A (1974), A. Descoeudres

et al. Plasma Sources Sci. Technol. (2003))


SINGLESINGLE--CRYSTAL SILICON NANOPARTICLESCRYSTAL SILICON NANOPARTICLES

Instability = Beginning of the agglomeration phase

Instability = Tool to monitor synthesis of nanocrystals


DUST PARTICLE GROWTH INSTABILITIES:DUST PARTICLE GROWTH INSTABILITIES:SPUTTERINGSPUTTERING

Measurement of the amplitude of current fundamental harmonics

0 100 200 300 400 500 600 700 800

0.5

0.55

0.6

0.65

0.7

0.75

0.8

Time (s)

Am

plitu

de (a

.u.)

Instability beginning

DC measurements


see

also

G. Praburam

et al. Phys. Plasmas (1996)D. Samsonov et al. Phys. Rev. E (1999)




0 100 200 300 400 500 600 700-0.02

-0.01

0

0.01

0.02

0.03

0.04

Time (s)

Am

plitu

de (a

.u.)

AC measurements

Instability beginningWell-defined

succession of

phases

P1…P3 Chaos RegularHF Chaos


see

also

G. Praburam





0 100 200 300 400 500 600 700-0.02

-0.01

0

0.01

0.02

0.03

0.04

Time (s)

Am

plitu

de (a

.u.)

AC measurements

Instability beginningWell-defined

succession of

phases

P1 P2 P3 P4


see

also

G. Praburam




M. Mikikian, L. Couëdel, M. Cavarroc, Y. Tessier, L. Boufendi, IEEE Trans. Plasma Sci. 36, 1012 (2008)M. Mikikian, M. Cavarroc, L. Couëdel, L. Boufendi, Phys. Plasmas 13, 092103 (2006)

As for electrical measurements:Changes in the global plasma emission

(increase)

If dust particle density is highPlasma equilibrium is affected

INSTABILITIES

5'' 1' 2' 7' 15' 16'

A change in electrical or optical measurements can be the indication of the presence of dust particles

and attract experimenter attention


3H (a.

u)

Time (s)

2nd

dust particlegeneration

3rd

dust particlegeneration

Aggregation Growth by surface deposition


Instability

M. Cavarroc, M. Mikikian, Y. Tessier, L. Boufendi, Phys. Rev. Lett. 100, 045001 (2008)

SUCCESSIVE GENERATIONSSUCCESSIVE GENERATIONSIN A SILANEIN A SILANE--BASED DISCHARGEBASED DISCHARGE

Cyclic formation of dust particles as long as the discharge is fed with precursors

Easily observed on electrical measurements







DUSTDUST--FREE SPACES: THE VOIDFREE SPACES: THE VOIDIn typical cc-rf

discharges a dust-free space appears close to the

plasma center

This void is induced by an ion drag force that pushes away negatively charged dust particles (J. Goree

et al. Phys. Rev. E (1999))

M. Mikikian, L. Couëdel, M. Cavarroc, Y. Tessier, L. Boufendi, New J. Phys. 9, 268 (2007)

The void appears when dust particles reach a sufficiently large size (charge)


SUCCESSIVE GENERATIONSSUCCESSIVE GENERATIONSIN A SPUTTERING DISCHARGEIN A SPUTTERING DISCHARGE


and the PKE-Nefedov

team, New J. Phys. 5, 19 (2003)


SUCCESSIVE GENERATIONSSUCCESSIVE GENERATIONSIN A SPUTTERING DISCHARGEIN A SPUTTERING DISCHARGE


and the PKE-Nefedov

team, New J. Phys. 5, 19 (2003)

see also L. Ravi

et al. Phys. Rev. E (2009)


Time (s)

Amplitud

e (a

.u.)


Correlation between electrical measurements, OES and LLS

Use of information from PKE-Nefedov

3H ~ free e-

Low density of "big" dust particles

High density of "small" dust particles

Global charge ~ similar

+


see also E.V. Johnson et al. Plasma Sources Sci. Technol. (2008)J.-C. Schauer

et al. Plasma Sources Sci. Technol. (2004)


Time (s)

Amplitud

e (a

.u.)




LLS ↑

: Dust particles grow in the void

LLS ↓

: Dust particles pushed away from plasma center

Sufficiently big to be detected

+





Time (s)

Amplitud

e (a

.u.)




I750.38

↑

: void opening

Dust particles are pushed away from plasma center continuing their

growth

I750.38

↓

: void starts to be filled by growing dust particles

+





Time (s)

Amplitud

e (a

.u.)




New dust particle generations emerge from inside the void

Confirmation by depositions performed at several distances

from electrode center

SEM analyses

+




M. MIKIKIAN – DSDP2 – Kiel – September 4th 2009M. Cavarroc, M. Mikikian, Y. Tessier, L. Boufendi, IEEE Trans. Plasma Sci. 36, 1016 (2008)

DEPOSITION OF DUST PARTICLESDEPOSITION OF DUST PARTICLESFROM DIFFERENT GENERATIONSFROM DIFFERENT GENERATIONS

Switching off the plasma when several generations coexistComplex dust cloud structure transferred to the deposition

Big (older) dust particles can be partly buried by new small dust

particles

Low sticking coefficient

M. MIKIKIAN – DSDP2 – Kiel – September 4th 2009M. Cavarroc, M. Mikikian, Y. Tessier, L. Boufendi, IEEE Trans. Plasma Sci. 36, 1016 (2008)

DEPOSITION OF DUST PARTICLESDEPOSITION OF DUST PARTICLESFROM DIFFERENT GENERATIONSFROM DIFFERENT GENERATIONS

Switching off the plasma when several generations coexistComplex dust cloud structure transferred to the deposition

Can be removed when venting too brutally the reactor to atmospheric

pressure

Useful (?) to see inner structure of the film

Big (older) dust particles can be partly buried by new small dust

particles

Low sticking coefficient

Wormhole to go back in time !!


50 100 150 200 250 300 350 400 4500

0.1

0.2

0.3

0.4

Tim e (s )

3H (a

.u.)

Tim e (s )

Freq

uenc

y (H

z)

50 100 150 200 250 300 350 400 450

52

54

56

58

60

3H (a.

u.)

Freq

uenc

y (H

z)

Time (s)

Time (s)Alternation of "high" and "less" ordered phases

High-ordered phasenew dust particle generation

Less-ordered phaseexpelling of big dust particles

Hypothesis: Void instability

SUCCESSIVE GENERATION INSTABILITIESSUCCESSIVE GENERATION INSTABILITIES

Appearance time:

a few seconds after plasma ignition

Frequency: range 40 -

60 Hz

Duration: whole plasma duration

M. Cavarroc, M. Mikikian, Y. Tessier, L. Boufendi, Phys. Plasmas 15, 103704 (2008)

Bumps: new generations


Very low frequency oscillation and rotation (sometimes !) of the

void regionVariant of the heartbeat instability ?

Heartbeat instability: see M. Mikikian

et al. New J. Phys. (2007), Phys. Rev. Lett. (2008)

INSTABILITIES DURING DUST PARTICLEINSTABILITIES DURING DUST PARTICLEFORMATION IN THE VOIDFORMATION IN THE VOID


EPS, ECA Vol. 27A, p. O-3.1B (2003)








Many diagnostics can be used to detect and follow dust particle growthElectrical, Optical

Very important for the well-controlled design of nanoparticles

A high density of dust particles leads to plasma disturbance

Many different types of instabilities can be observed

Dust particle formation in plasma environments is relatively commonAstrophysics, Industry, Fusion

Control of dust particle formation is fundamental for applications

Dust particle formation is a cyclic phenomenonas long as precursors are provided

Dust-free spaces like the void play a crucial role


THANK YOU

FORMATION OF DUST PARTICLES AND RELATED PHENOMENA filem. mikikian – dsdp2 – kiel – september 4. th. 2009. formation of dust particles in a plasma why ? where ? evidence and diagnostics

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