© Fraunhofer ILT

Klaus Bergmann

EUV Source Workshop, October,9th, Dublin, Ireland

Discharge based EUV Sources for Metrology

© Fraunhofer ILT

Overview

Introduction

Technology and current status of HCT sources at ILT

Brilliance scaling for 13.5 nm

Conclusions

© Fraunhofer ILT

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History of EUV sources at ILT

Laser

Tin Supply

Electrode 1 Electrode 2

Laser

Tin Supply

Electrode 1 Electrode 2

1997 2001 2003 2011 2006 year

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Current XUV activities at ILT

Development of sources for EUV

lithography based on tin vacuum arc

(together with Xtreme)

Sources for metrology in the range

soft x-ray and EUV

XUV-Applications

(Support of TOS, RWTH Aachen University)

EUVL source development

Interference lithography

X-ray microscopy

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Technical base: Philips HCT source

Philips Xenon Source

ASML a-demo Tool

HCT principle was

patented by ILT

collaboration on

power scaling for use

as EUVL source

source delivered first

light in ASML a-demo

tool

currently used in the

field as metrology source

(mirror contamination,

optics characterization)

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Next Generation Source at Fraunhofer ILT

technical base is the HCT source

developed with Philips EUV

new system allows for higher

input power and pulse energy

simplified and more compact

source head design

emission in the soft x-ray to

extreme ultraviolet range

increased electrode lifetime

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Technical concept

Scheme of electrode system

max. input power: 25 kW

max. pulse energy: 20 J

emission at 13.5nm: >50 W/(2psr 2%b.w.)

typical plasma length: 3-5 mm

accessible collection angle: >80°

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Selected examples of applications (1)

Inband Energy Monitor

Absolute calibration of EUV diagnostics

Gracing / Normal Incidence Reflectometer

Inband Screen Tool

0,00

20,00

40,00

60,00

80,00

100,00

60 65 70 75 80 85 90

PS328704 3rd

PS 328704 1st

PS328704 2nd

ML-Mirror

Ru-Mirror

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Selected examples of applications (2)

Interference Lithography (11 nm) X-Ray Microscopy

(2.9 nm)

9 10 11 12 13 14 15

0

10

20

30

40

50

60

70

PU

LS

E IN

TE

NS

ITY

[ m

J/ (2psr

nm

) ]

WAVELENGTH [ nm ]

PbS nanocrystals for solar cells

Nitrogen emission spectrum

Xe/Ar emission spectrum

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Progress in Electrode lifetime

Pinch Plasma

Sputtering due to pinch plasma

Cathode spots

erosion due to sputtering and

cathode spots

most critical consumable is cathode

intermediate plate allows for

reducing the influence of cathode erosion

improvement by use of other metal

envisioned interval for exchange of

electrodes is 1Gshot

Cathode after 100 Mshot

Molybdenum Metal with higher

melting point

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How do we measure “Peak Brilliance”

pinhole camera + Zr coated silicon nitride window

2

2/1

5.13

r

CEEfL nmin

peakp

-2000 -1500 -1000 -500 0 500 1000 1500 20000

1

2

3

4

5

6

7

BR

ILL

IAN

CE

[ a

rb.

un

its ]

RADIUS [ µm ]

calibrated energy monitor

Inband power (CE13.5nm) Emission profile (r1/2, )

f(r) f : repetition rate

Ein : electrical pulse energy

2

2/1

0

2

r

drrrf

f(r=0) = 1.0

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Parameter studies (1): Brilliance Efficiency

1 2 3 4 5 60,0

0,5

1,0

1,5

2,0

EF

FIC

IEN

CY

[ W

/ k

W m

m2 s

r ]

PULSE ENERGY [ J ]

peak brilliance at 300 Hz operation

red rhomb for old system at 8.7 kW

demonstrated 2.0 W/(kW mm2 sr)

at a pulse energy of 6.1 J

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Parameter studies (2): Variation of pulse energy

peak brilliance at 1000 Hz operation

low variation of profile coefficients

over wide range of pulse energies

-1500 -1000 -500 0 500 1000 15000,0

0,5

1,0

INT

EN

SIT

Y [

no

rm. ]

RADIUS [µm]

p:<eb_xuvquelle.laborbuch.bergmann.2012.120920>pinchprofile.opj

Normalized profiles for different energies

Ein / J r1/2 / µm *r1/22/ mm2

2.3 269 2.1 0.15

3.1 236 3.2 0.18

4.0 244 3.7 0.22

4.9 228 4.2 0.22

5.9 232 4.3 0.23

6.6 225 4.3 0.22

7.6 218 4.4 0.21

8.4 225 4.5 0.23

Brilliance efficiencies:

0.9 – 1.4 W/kWmm2sr

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Demonstration of 21 W/(mm2sr)

-2,0 -1,5 -1,0 -0,5 0,0 0,5 1,0 1,5 2,0-8

-7

-6

-5

-4

-3

-2

-1

0

1

VO

LT

AG

E [ k

V ]

TIME [ ms ]

0,00

0,01

0,02

0,03

0,04

0,05

0,06

DIO

DE

VO

LT

AG

E [ V

]

-1500 -1000 -500 0 500 1000 15000

1

2

3

4

5

6

7

PE

AK

BR

ILL

IAN

CE

[ m

J/m

m2sr]

RADIUS [ µm ]

2

2/1r

CEEfL in

peakp

f (repetition rate) : 3.3 kHz

Ein (pulse energy) : 6.0 J

CE (conversion eff.) : 0.3 %/2psr

(profile factor) : 5.8

r1/2 (radius) : 155 µm

Diode and voltage for 3.3 kHz, 6.0J Profile for 3.3 kHz, 6.0J

© Fraunhofer ILT

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Demonstration of 21 W/(mm2sr)

-2,0 -1,5 -1,0 -0,5 0,0 0,5 1,0 1,5 2,0-8

-7

-6

-5

-4

-3

-2

-1

0

1

VO

LT

AG

E [ k

V ]

TIME [ ms ]

0,00

0,01

0,02

0,03

0,04

0,05

0,06

DIO

DE

VO

LT

AG

E [ V

]

-1500 -1000 -500 0 500 1000 15000

1

2

3

4

5

6

7

PE

AK

BR

ILL

IAN

CE

[ m

J/m

m2sr]

RADIUS [ µm ]

2

2/1r

CEEfL in

peakp

f (repetition rate) : 3.3 kHz (2.5 kHz)

Ein (pulse energy) : 6.0 J (7.0 J)

CE (conversion eff.) : 0.3 %/2psr (0.4 %/2psr)

(profile factor) : 5.8 (4.8)

r1/2 (radius) : 155 µm (180 µm)

22.4 W/mm2sr

Diode and voltage for 3.3 kHz, 6.0J Profile for 3.3 kHz, 6.0J

© Fraunhofer ILT

P:<ordner>name.ppt

Scaling Potential >50 W/(mm2sr)

-1500 -1000 -500 0 500 1000 15000,0

0,2

0,4

0,6

0,8

1,0

NO

RM

. B

RIL

LIA

NC

E

RADIUS [ µm ]

260 µm diameter source profile (full) and profile from 21 W/mm2sr demonstration (dotted)

estimation of achievable brilliance

by multiplying realistic and already

demonstrated best of parameters

experience with previous system:

gas flow conditions is the key

optimization parameter

srmm

W

r

CEEfL in

peak 22

2/1

6.70p

20 kW 0.53 %

4.5 130 µm

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Considerations on Source-Collector-Module

Normal Incidence collector (Ray Tracing)

example for source-collector-module

with typical distance:

~1m source-mirror and mirror-focus

relaxed requirements for debris-mitigation

homogeneous illumination of sample over

~50 µm “easy” to achieve

mirror

source

focus

Intensity profile at IF

-50 -40 -30 -20 -10 0 10 20 30 40 5010000

15000

20000

INT

EN

SIT

Y [ a

rb. u

nits ]

RADIUS [ µm ]

p:<ex_xuvquelle.laborbuch.bergmann.2012.120920>if-homogeneity.opj

50 µm

homogeneity : <1.0%

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P:<ordner>name.ppt

Conclusions

next discharge source has been taken in operation at ILT

technical base is status of development together with Philips EUV

new system is more compact and covers a larger parameter range

work on brilliance scaling just has started

demonstration of 21 W/(mm2 sr) into 2%b.w. for 13.5 nm at 20 kW input power

optimization potential for >50 W/mm2sr based on experimental data has been identified

© Fraunhofer ILT

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Acknowledgements

Markus Benk (currently at CXRO in Berkeley)

Jochen Vieker

Federal State NRW, Germany for financial support