1

www.DRAFT.ugent.be

Rotatable magnetron sputtering:

downscaling for a better understanding

R. De Gryse

2

www.draft.ugent.be

Overview

Target

Magnets

plasma

N

S

S

Figure after P. Sieck, 38th Annual Technical Conference Proceedings (1995) 281

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

2

3

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Benefits of rotatables

1. Better sputter materials inventory

2. Better target materials utilization

3. Better cooling efficiency allowing higher power densities

and consequently higher deposition rates

4. Higher stability in reactive sputtering processes

5. Reduced debris formation

6. Better sputtering of magnetic materials

7. No or little variation in sputtering behaviour due to race

track deepening

8. Better disappearing anode behaviour in dual magnetron

sputtering

9. Higher allowable power densities make rotatables HIPIMS

friendly.

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

4

www.draft.ugent.be

Drawbacks of rotables

1. Complexity of the equipment, translates itself into cost.

2. Almost always working in unbalanced mode

3. Availability of targets sometimes a nightmare requiring

complex metallurgical techniques such as plasma spraying,

HIPping (Hot Isostatic Pressing) or casting. Also planars are

suffering from these problems but mostly to a lesser

degree.

4. Not available on a laboratory scale.

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

3

5

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Scaling down for fundamental studies

target in vacuum chamber

changeable ISO-K 100

To power supply

gear box

to water cooling

20 cm

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

6

www.draft.ugent.be

Typical features of rotating magnetrons

•Influence of target redeposition

•Influence of speed of rotation

•Beaming effect

•Rotatable magnetrons and HIPIMS

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

4

7

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Redeposition on the target : Discharge voltage behaviour

250

270

290

310

330

350

370

0 1 2 3

oxygen flow (sccm)

discharge voltage (V)

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

Discharge voltage for stationary target

metallic

poisoned

8

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Redeposition on the target : sputter cleaning

340

320

300

280

260

240

dis

charg

e v

oltage (

V)

5004003002001000

time (s)

poisoned mode metallic mode

In poisoned mode : faster sputter cleaning than in metallic mode

Reason : the deposited layer is much thinner because the

deposition rate is much lower

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

5

9

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Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

Redeposition on the target : understanding

Preconditioning

Poisoned mode (2.5 sccm)

Preconditioning

metal mode (1.8 sccm)

Chemisorption

Redeposition

oxide

metal

10

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Redeposition on the target : Deposition profile

12840

14

12

10

8

6

4

2

012840

200

150

100

50

0

Å/s

7

6

5

4

3

2

1

0

Å/s

distance (cm) distance (cm)

dis

tance

(cm

)

(a) (b)

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

Simulation performed with SIMTRA

K. Van Aeken, S. Mahieu, D. Depla J. Phys. D : Appl. Phys. 41 (2008) 205307

6

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Target rotation : Influence of rotating speed

250

270

290

310

330

350

370

0 1 2 3

oxygen flow (sccm)

discharge voltage (V)

0.0 RPM

0.2 RPM

0.6 RPM

0.8 RPM

1.0 RPM

2.0 RPM

4 0 RPM

8.0 RPM

21 RPM

60 RPM

Hysteresis shifts to lower oxygen flow

on increasing the rotation speed

D. Depla, J. Haemers, G. Buyle, R. De Gryse, J. Vac. Sci. Technol. Science A 24

(2006) 934

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

12

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Target rotation : Influence of rotation speed

2.2

2.0

1.8

1.6

1.4

1.2

1.0

0.8

transi

tion p

oin

t (s

ccm

)

86420

rotation speed (RPM)

metallic mode

poisoned mode

transition point on addition transition point on removal

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

7

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Target rotation : Simulation result2.4

2.2

2.0

1.8

1.6

1.4

1.2

1.0

0.8

transi

tion p

oin

t (s

ccm

)

86420

rotation speed (RPM)

metallic mode

poisoned mode

WRONG : gradual change but

experimental abrupt effect

WRONG : minor effect of the rotation

speed

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

14

www.draft.ugent.be

Target rotation : Simulation result

2.4

2.2

2.0

1.8

1.6

1.4

1.2

1.0

0.8

transi

tion p

oin

t (s

ccm

)

86420

rotation speed (RPM)

metallic mode

poisoned mode

(b)

RIGHT : abrupt effect is mimicked

RIGHT : a more gradual decrease

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

8

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Beaming effects : Mass distribution of negative ions

101

102

103

104

105

106

Cps

(a.u

.)

300250200150100500E (eV)

AlO2-

O2-

AlO-

O-

101

102

103

104

105

Cps

(a.u

.)

300250200150100500E (eV)

YO2-

O2-

YO-

O-

Not only O- , but alsoO2

-, MO-, MO2-

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

S. Mahieu, W.P. Leroy, K. Van Aeken, D. Depla

J. Appl. Phys. 106 (2009) 093302

16

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Beaming effects : Direction of negative O- ions

'O exp' 'O SiMTRA' 'O/Al SiMTRA (a.u.)' 'magnetron'

0° 10°20°

-30° 30°

-20°-10°

Al Y

'O exp' 'O SiMTRA' 'O/Y SiMTRA (a.u.)' 'magnetron'

0° 10°20°

-30° 30°

-20°-10°

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

9

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Beaming effects : Direction of negative O- ions

'O exp' 'O SiMTRA' 'O/Al SiMTRA (a.u.)' 'magnetron'

0°

50°

10°20°

30°

40°

60°

70°

80°

-10°-20°

-30°

-40°

-50°

-60°

-70°

-80°

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

18

www.draft.ugent.be

Beaming effect : comparing planar with rotatable

Planar

Rotatable

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

10

19

www.draft.ugent.be

Beaming effect : influence on the coatingOverview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

S SS

N

N

N

S SS

N

N

N

S SS

N

N

N

S SS

N

N

N

Position 1 and 4 : transition

Position 2 : Tc<69 K

Position 3 : no Tc

20

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Rotating magnetrons and HIPIMSOverview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

W. P. Leroy, S. Mahieu, D. Depla, A. P. Ehiasarian,

accepted for publication in JVST A (DOI: 10.1116/1.3271136)

101

102

103

104

105

106

107

Counts

(a.u

.)

45403530252015105Mass (amu)

Al++

Al+ Ar+

Ar++

DC mode Stationary HiPIMS mode Rotating HiPIMS mode

11

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Conclusions

• If the cathodes are available, rotatable magnetrons are the winning horses

• Rotatable magnetrons are a different piece of equipment as compared to planars

� High importance of target redeposition outside the

racetrack

� Influence of the rotation speed on hysteresis behaviour

� Important beaming effects

� Well adapted for HIPIMS applications

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements

22

www.draft.ugent.be

Acknowledgements

D. Depla

S. Mahieu

W. Leroy

X.Y. Li

K. Van Aeken

J. Haemers

G. Buyle

J. Musschoot

K. Eufinger

A. Segers

B. Ehiasarian

R. Snyders

S. Konstandinitis

Financial support

IWT project 60030

Flemish scientific

fund

Overview

Benefits of RM

Drawbacks of RM

Scaling down

Features of RM

Redeposition

Target rotation

Beaming effects

RM and HIPIMS

Conclusions

Acknowledgements